ATF2 Antibody

What is ATF2 and why is it a significant target for antibody-based research?

ATF2 (Activating Transcription Factor 2) functions as a critical transcription factor in the bZIP family that regulates gene expression in response to stress and growth factor stimuli. It plays crucial roles in cellular stress responses, cell proliferation, and differentiation by binding to cAMP response elements (CREs) in target gene promoters . ATF2 is particularly significant as a research target because it undergoes post-translational modifications, including phosphorylation at specific threonine residues (Thr69 and Thr71), which are essential for its transcriptional activity . Furthermore, ATF2 exhibits histone acetyltransferase activity, specifically acetylating histones H2B and H4, thereby influencing chromatin structure and gene accessibility . The multifaceted functions of ATF2 in cellular signaling pathways make it a valuable target for investigating mechanisms underlying cancer development, neurodegenerative disorders, and stress responses.

What are the primary types of ATF2 antibodies available for research, and how do they differ in experimental applications?

The primary types of ATF2 antibodies include monoclonal antibodies like F2BR-1, which is a mouse monoclonal IgG1 kappa light chain antibody capable of detecting ATF2 proteins from multiple species (mouse, rat, and human) . These antibodies are available in both non-conjugated forms and various conjugated formats, including agarose, horseradish peroxidase (HRP), phycoerythrin (PE), fluorescein isothiocyanate (FITC), and multiple Alexa Fluor® conjugates .

Phospho-specific antibodies, such as those targeting phosphorylated Ser112, are particularly valuable for monitoring activation states of ATF2 in response to stimuli . The experimental applications differ as follows:

These different formats enable researchers to select the most appropriate antibody based on their specific experimental requirements, whether studying total ATF2 expression or its phosphorylation state.

How does ATF2 protein function in cellular signaling pathways, and what implications does this have for antibody selection?

ATF2 functions as a critical node in multiple cellular signaling pathways. ATF2 becomes activated through phosphorylation by stress-activated kinases in response to stress and cytokine stimuli . Its transcriptional activity depends on heterodimerization with AP1 family members, particularly c-Jun, which significantly enhances its DNA binding and transcriptional capacity . ATF2 regulates AP1-responsive genes including cyclin A, IFN-β, and TNF-α, thereby influencing cell cycle progression and immune responses . Additionally, ATF2 participates in the DNA damage response through phosphorylation by ATM, which is required for intra-S phase checkpoint control .

These diverse functions have significant implications for antibody selection:

• For studying ATF2 activation states, phospho-specific antibodies targeting Thr69/71 or Ser112 are essential to distinguish between inactive and active forms.

• When investigating protein-protein interactions, antibodies with epitopes outside the dimerization domain should be selected to avoid interference with binding partners.

• For nuclear localization studies, antibodies that recognize nuclear localization signals without masking them are preferable, as nuclear localization of ATF2 has been associated with poor prognosis in certain cancers .

• When examining ATF2's role in ubiquitination processes, antibodies that don't interfere with ubiquitination sites are necessary, as ATF2 ubiquitination is dimerization-dependent .

Understanding these signaling pathways is crucial for selecting appropriate antibodies that won't interfere with the biological processes being studied.

What are the optimal conditions for using ATF2 antibodies in Western blotting applications?

Optimizing Western blotting conditions for ATF2 detection requires careful consideration of several parameters. Based on established protocols, researchers should implement the following methodological approach:

Sample preparation should include proper cell lysis using buffers containing protease and phosphatase inhibitors to preserve the phosphorylation state of ATF2. For gel electrophoresis, 8% polyacrylamide gels provide optimal resolution for ATF2, which has a molecular weight of approximately 70 kDa (full-length) or 55 kDa (truncated forms) . Transfer conditions should be optimized for high molecular weight proteins, typically using wet transfer at constant amperage (250-300 mA) for 1.5-2 hours.

For primary antibody incubation, the F2BR-1 monoclonal antibody at a 1:500-1:1000 dilution in 5% BSA/TBST overnight at 4°C yields consistent results . Secondary antibody selection should match the host species of the primary antibody (anti-mouse HRP for F2BR-1). For enhanced chemiluminescence detection, extended exposure times may be necessary to detect low-abundance phosphorylated forms.

When stripping and reprobing membranes for total and phosphorylated ATF2, gentle stripping buffers should be used to preserve membrane integrity, allowing sequential detection of different forms . To confirm specificity, positive controls (cell lysates with known ATF2 expression) and negative controls (ATF2-knockout cells) should be included in each experiment.

By adhering to these optimized conditions, researchers can achieve reliable and reproducible detection of both total and phosphorylated ATF2 in Western blotting applications.

How should researchers design experiments to study ATF2 phosphorylation dynamics using phospho-specific antibodies?

Designing experiments to study ATF2 phosphorylation dynamics requires a comprehensive approach that captures temporal changes in phosphorylation states. Researchers should consider the following methodological framework:

• Cell line selection: Choose cell lines with detectable baseline ATF2 expression. For optimal results, cells should be 75-90% confluent at the time of treatment, with approximately 30,000 HeLa cells per well being appropriate for most assays .

• Stimulation conditions: Select appropriate stimuli known to activate ATF2, such as UV radiation, stress inducers, growth factors, or cytokines. Include time-course experiments (5, 15, 30, 60 minutes) to capture rapid phosphorylation changes.

• Phosphorylation site-specific approach: Utilize antibodies that specifically recognize phosphorylated ATF2 at Thr69/71 or Ser112, which are critical for transcriptional activity .

• Controls: Include both positive controls (cells treated with known ATF2 activators) and negative controls (phosphatase-treated lysates or inhibitor-pretreated cells) .

The following experimental design table provides a structured approach:

For data analysis, normalization should be performed using total ATF2 levels or GAPDH expression as internal controls . Quantitative assessments should calculate the ratio of phosphorylated to total ATF2, plotted against time to visualize phosphorylation dynamics. This comprehensive approach enables researchers to accurately characterize the temporal dynamics of ATF2 phosphorylation in response to various stimuli.

What considerations are important when using ATF2 antibodies in immunoprecipitation studies investigating protein-protein interactions?

When designing immunoprecipitation (IP) experiments to investigate ATF2 protein-protein interactions, researchers must address several critical methodological considerations to ensure reliable and interpretable results:

First, antibody selection is crucial. Choose antibodies with epitopes that don't interfere with protein-protein interaction domains, particularly the leucine zipper region which mediates dimerization with partners like c-Jun . The F2BR-1 monoclonal antibody has been validated for IP applications and can effectively capture ATF2 complexes .

Lysis conditions must preserve native protein interactions. Use non-denaturing buffers (typically containing 150mM NaCl, 1% NP-40 or Triton X-100, 50mM Tris pH 7.5) supplemented with protease and phosphatase inhibitors to maintain interaction integrity . When investigating phosphorylation-dependent interactions, phosphatase inhibitors are essential.

For co-immunoprecipitation protocols, researchers should:

• Prepare cell lysates (1-2 mg total protein) in non-denaturing conditions

• Pre-clear lysates with protein A/G beads to reduce non-specific binding

• Incubate cleared lysates with ATF2 antibody (2-5 μg) overnight at 4°C

• Capture antibody-protein complexes with protein A/G beads for 2-4 hours

• Wash stringently (at least 4 times) while maintaining complex integrity

• Elute complexes and analyze by immunoblotting for ATF2 and suspected binding partners

When investigating dimerization-dependent processes like ubiquitination, researchers should consider additional controls such as immunodepleting specific interaction partners (c-Jun, c-Fos) to assess their contribution to ATF2 regulation . To validate interactions, reciprocal IP (pulling down with partner protein antibody and blotting for ATF2) should be performed.

This methodological approach provides robust evidence for genuine protein-protein interactions while minimizing artifacts commonly encountered in co-immunoprecipitation experiments.

How does ATF2 ubiquitination influence protein stability, and what methodologies can detect this process?

ATF2 ubiquitination represents a critical regulatory mechanism controlling protein stability and function. Research indicates that ATF2 ubiquitination is dimerization-dependent, with heterodimeric partnerships significantly influencing the degree of ubiquitination . Specifically, interaction with c-Jun and c-Fos has been shown to affect ATF2 ubiquitination levels, highlighting the complex interplay between protein-protein interactions and post-translational modifications .

To effectively detect and quantify ATF2 ubiquitination, researchers should employ the following methodological approach:

For in vivo ubiquitination assays, the established protocol involves:

• Co-transfection of His-tagged ATF2 (4 μg) with HA-tagged ubiquitin (3 μg) into appropriate cell lines

• Cell lysis under denaturing conditions (6M guanidinium HCl) to disrupt non-covalent interactions

• Purification of His-tagged proteins using nickel resins

• Analysis by SDS-PAGE and immunoblotting with anti-HA antibodies to detect ubiquitin-conjugated species

This methodology allows visualization of the characteristic high-molecular-weight smear representing poly-ubiquitinated ATF2. To investigate the role of specific dimerization partners, immunodepletion experiments can be performed:

To further characterize the ubiquitination process, researchers can employ mutational analysis of ATF2 dimerization domains, proteasome inhibitors (MG132) to accumulate ubiquitinated species, and cycloheximide chase assays to assess protein stability. Together, these methodological approaches provide comprehensive insights into the complex relationship between ATF2 dimerization and ubiquitin-mediated regulation.

What role does ATF2 play in cancer progression, and how can antibody-based techniques help elucidate these mechanisms?

ATF2 exhibits context-dependent roles in cancer progression, functioning as either a tumor suppressor or oncogene depending on cellular context. In skin cancer, genetic evidence indicates a tumor suppressor role for ATF2. Studies using keratinocyte-specific ATF2 deletion (K14.ATF2f/f mice) demonstrated significantly increased papilloma incidence and prevalence when subjected to two-stage skin carcinogenesis protocols . These findings were corroborated by enhanced anchorage-independent growth of ATF2-deficient keratinocytes in vitro .

Mechanistically, loss of ATF2 in skin tumors is associated with reduced expression of presenilin1, leading to enhanced β-catenin and cyclin D1 levels, and reduced Notch1 expression . Importantly, clinical samples of squamous and basal cell carcinomas show reduced nuclear ATF2 alongside increased β-catenin expression compared to normal skin, supporting the translational relevance of these findings .

Antibody-based techniques provide powerful tools for elucidating these mechanisms:

• Immunohistochemistry using validated ATF2 antibodies can assess subcellular localization (nuclear vs. cytoplasmic) in tumor samples, which correlates with prognosis in certain cancers like melanoma .

• Phospho-specific antibodies can determine ATF2 activation status in different tumor types, revealing pathway dependencies.

• Chromatin immunoprecipitation (ChIP) using ATF2 antibodies can identify direct transcriptional targets in normal versus cancer cells, illuminating altered gene regulation programs.

• Proximity ligation assays can visualize ATF2 interactions with other transcription factors (c-Jun, p53) in intact tumor tissues.

A comparative analysis of ATF2 roles across cancer types reveals:

By employing these antibody-based approaches, researchers can develop a comprehensive understanding of ATF2's multifaceted roles in cancer progression, potentially revealing new therapeutic vulnerabilities.

How do phosphorylation and other post-translational modifications regulate ATF2 function, and what experimental approaches can track these modifications?

ATF2 function is intricately regulated by a complex network of post-translational modifications (PTMs), with phosphorylation playing a particularly critical role. Understanding these modifications requires sophisticated experimental approaches using specific antibodies and advanced analytical techniques.

Phosphorylation of ATF2 at Thr69 and Thr71 by stress-activated kinases represents a key activation mechanism that is essential for transcriptional activity . Additionally, Ser112 phosphorylation provides another regulatory layer that can be monitored using phospho-specific antibodies . Myc-induced phosphorylation contributes to ATF2 stability, illustrating the interconnected nature of phosphorylation and protein turnover .

Beyond phosphorylation, ATF2 undergoes ubiquitination in a dimerization-dependent manner, directly affecting protein stability and availability . Furthermore, ATF2 itself exhibits histone acetyltransferase activity, specifically acetylating histones H2B and H4, revealing a dual role as both a modified substrate and an enzyme that confers modifications .

To comprehensively track these modifications, researchers should implement the following experimental strategies:

• Phosphorylation mapping:

  • Western blotting with phospho-specific antibodies against Thr69/71 and Ser112

  • Phosphatase treatment controls to confirm specificity

  • Kinase inhibitor studies to identify responsible signaling pathways

  • Mass spectrometry to discover novel phosphorylation sites

• Ubiquitination analysis:

  • In vivo ubiquitination assays using tagged ubiquitin constructs

  • Proteasome inhibitor treatments to accumulate ubiquitinated species

  • Immunoprecipitation under denaturing conditions to preserve ubiquitin linkages

• Functional correlation:

  • Reporter gene assays with wild-type versus phospho-mutant ATF2

  • Chromatin immunoprecipitation to assess binding to target genes

  • Cell-based assays measuring proliferation, apoptosis, and stress responses

The Cell-Based ELISA approach offers particular advantages for studying phosphorylation dynamics, as it allows monitoring ATF2 phosphorylation in intact cells with temporal resolution and normalization capabilities . This technique enables researchers to directly correlate stimulation conditions with phosphorylation status and downstream functional outcomes.

By integrating these experimental approaches, researchers can construct a comprehensive understanding of how various PTMs collectively regulate ATF2 function in both normal and pathological contexts.

What are common technical challenges when working with ATF2 antibodies, and how can researchers overcome them?

Researchers frequently encounter several technical challenges when working with ATF2 antibodies that can compromise experimental outcomes. Here, I outline common issues and provide methodological solutions based on published protocols and empirical evidence.

Challenge 1: Weak or inconsistent signal detection
This frequently stems from low abundance of ATF2, particularly phosphorylated forms, in certain cell types. To overcome this limitation:

• Enrich ATF2 through immunoprecipitation before immunoblotting when working with low-abundance samples

• Optimize cell lysis using buffers containing strong detergents (1% SDS) followed by dilution before immunoprecipitation

• Increase antibody concentration and extend incubation time (overnight at 4°C)

• Use signal enhancement systems like biotin-streptavidin amplification or high-sensitivity chemiluminescent substrates

Challenge 2: High background in immunofluorescence and immunohistochemistry
Non-specific binding can obscure genuine ATF2 signal. Implement these optimization strategies:

• Extend blocking time (2-3 hours) with 5% BSA and 5% normal serum from secondary antibody host species

• Include additional washing steps (5-6 washes) with 0.1% Tween-20 in PBS

• Titrate primary antibody concentration (typically 1:100-1:500 dilution range) for optimal signal-to-noise ratio

• Pre-absorb antibodies with cell lysates from ATF2-knockout cells when available

Challenge 3: Cross-reactivity with related transcription factors
Due to sequence homology among bZIP family members, cross-reactivity can occur. Address this by:

• Validating antibody specificity using ATF2-knockout or knockdown samples as negative controls

• Confirming immunoreactive band size (70 kDa for full-length ATF2, 55 kDa for truncated forms)

• Using peptide competition assays to confirm epitope specificity

• Performing parallel experiments with multiple antibodies targeting different ATF2 epitopes

Challenge 4: Detecting differential subcellular localization
Nuclear versus cytoplasmic distribution of ATF2 has functional significance but can be difficult to resolve:

• Use cell fractionation followed by Western blotting to biochemically separate compartments

• For immunofluorescence, optimize fixation conditions (4% paraformaldehyde for 10 minutes preserves nuclear structure)

• Include co-staining with compartment-specific markers (DAPI for nucleus, α-tubulin for cytoplasm)

• Quantify nuclear-to-cytoplasmic ratio using digital image analysis software

By systematically addressing these challenges with appropriate methodological adjustments, researchers can significantly improve the reliability and sensitivity of ATF2 antibody-based experiments.

How can researchers optimize Cell-Based ELISA protocols for studying ATF2 phosphorylation in different cell types?

Optimizing Cell-Based ELISA protocols for studying ATF2 phosphorylation requires careful consideration of multiple parameters to ensure sensitivity, specificity, and reproducibility across different cell types. Based on established methodologies, researchers should implement the following optimization strategy:

Cell Type-Specific Considerations:
Different cell lines express varying levels of ATF2 and respond differently to stimuli. For adherent cells, direct seeding is appropriate, while suspension cells require additional preparation:

• Coat plates with 100 μl of 10 μg/ml Poly-L-Lysine for 30 minutes at 37°C before seeding suspension cells

• Use 8% formaldehyde rather than standard 4% for suspension cell fixation to ensure adequate attachment

Cell Density Optimization:
The optimal cell number varies by cell type and must be empirically determined:

• For HeLa cells, 30,000 cells per well in a 96-well format provides optimal results

• For smaller cells (lymphocytes), increase density to 50,000-100,000 cells per well

• For larger cells (fibroblasts), reduce to 10,000-20,000 cells per well

• Always aim for 75-90% confluence at the time of treatment

Stimulation Parameters:
To effectively capture ATF2 phosphorylation events:

• Include time course experiments (5-60 minutes) to identify optimal phosphorylation windows

• Test multiple stimuli concentrations to establish dose-response relationships

• For UV stimulation, determine cell type-specific UV sensitivity

• Include positive control stimuli known to activate ATF2 (e.g., anisomycin for p38 pathway)

Normalization Strategies:
To account for well-to-well variations, implement multiple normalization approaches:

• Use anti-GAPDH antibody as an internal loading control

• Employ Crystal Violet whole-cell staining to normalize for cell number

• Include antibodies against total ATF2 to calculate phosphorylation/total protein ratios

The following optimization matrix can guide parameter selection for different cell types:

By systematically optimizing these parameters for each cell type, researchers can establish robust Cell-Based ELISA protocols for studying ATF2 phosphorylation that yield reproducible and physiologically relevant results.

What approaches can resolve contradictory data when comparing different ATF2 antibodies or detection methods?

1. Comprehensive antibody validation:
Begin by validating each antibody through multiple complementary approaches:

• Verify epitope specificity using peptide competition assays

• Confirm target specificity using ATF2-knockout or knockdown samples

• Assess reactivity in multiple species if cross-species comparisons are involved

• Document exact antibody clone, lot number, and preparation to identify batch-specific variations

2. Cross-platform method comparison:
Implement parallel analyses using orthogonal detection methods:

• Compare Western blotting, ELISA, and immunofluorescence results

• Verify phosphorylation status using mass spectrometry as a reference method

• Assess functional outcomes using reporter gene assays or chromatin immunoprecipitation

• Document protocol differences that might explain discrepancies (lysis conditions, fixation methods)

3. Controlled side-by-side experiments:
Design experiments to directly compare antibodies under identical conditions:

• Process the same samples in parallel with different antibodies

• Include gradient loading to assess linearity of detection

• Test multiple antibody concentrations to determine optimal working range

• Document image acquisition parameters for immunofluorescence comparisons

4. Context-dependent interpretation:
Consider biological explanations for apparently contradictory results:

• Different antibodies may recognize distinct ATF2 conformations or modifications

• Certain dimerization partners might mask specific epitopes

• Nuclear versus cytoplasmic localization may affect antibody accessibility

• Post-translational modifications might alter antibody recognition sites

The following decision matrix can guide resolution of common discrepancies:

How are ATF2 antibodies being utilized in cancer biomarker research, and what methodological considerations are important?

ATF2 has emerged as a potential biomarker in various cancer types, with particular significance in melanoma, skin cancer, and other malignancies. ATF2 antibody-based approaches are revealing complex patterns of expression, localization, and activation that correlate with disease progression and prognosis. Several methodological considerations are critical for biomarker development:

Nuclear localization of ATF2 has been correlated with poor prognosis in melanoma patients, highlighting the importance of subcellular distribution analysis . This finding underscores the need for immunohistochemical protocols that precisely distinguish between nuclear and cytoplasmic ATF2 localization. Conversely, in skin cancers, reduced nuclear ATF2 expression coupled with increased β-catenin has been observed, suggesting context-dependent roles across cancer types .

For tissue microarray analysis of patient samples, researchers should implement:

• Standardized staining protocols with validated antibody dilutions

• Digital image analysis with nuclear/cytoplasmic segmentation

• Quantitative scoring systems correlating with clinical outcomes

• Multiplex staining to assess ATF2 in relation to interaction partners (c-Jun, β-catenin)

Phosphorylation status of ATF2 provides critical information about activation state and may serve as a predictive biomarker for therapy response. Cell-Based ELISA approaches can be adapted for patient-derived samples to quantify phospho-ATF2/total ATF2 ratios .

Several methodological considerations are essential for biomarker validation:

• Pre-analytical variables must be controlled, including tissue fixation time, processing methods, and storage conditions.

• Technical validation requires assessment of intra- and inter-observer reproducibility, antibody lot-to-lot consistency, and correlation with other detection methods.

• Clinical validation necessitates appropriate cohort sizes with adequate statistical power, multivariate analysis controlling for confounding variables, and ideally prospective studies.

The emerging liquid biopsy field presents opportunities to detect ATF2 in circulating tumor cells or exosomes, requiring highly sensitive immunoassays. These approaches must be calibrated against established tissue-based methods using paired samples to establish concordance.

By addressing these methodological considerations, researchers can develop robust ATF2 antibody-based biomarker assays with potential clinical utility in cancer diagnosis, prognosis, and therapeutic monitoring.

What is the current understanding of ATF2's role in DNA damage response, and how can researchers investigate this function?

ATF2 plays a multifaceted role in the DNA damage response (DDR) pathway, functioning beyond its classical transcription factor activity. Current understanding indicates that ATF2 undergoes phosphorylation by ATM (Ataxia Telangiectasia Mutated) kinase, a central regulator of DNA damage signaling . This phosphorylation is required for intra-S phase checkpoint control and facilitates ATF2's colocalization with components of the Mre11-Rad50-Nbs1 (MRN) complex within DNA damage repair foci .

To investigate ATF2's function in DNA damage response, researchers should implement the following methodological approaches:

1. Visualization of ATF2 recruitment to DNA damage sites:

• Laser microirradiation coupled with real-time imaging of fluorescently tagged ATF2

• Immunofluorescence detection of endogenous ATF2 at γH2AX-positive damage foci

• Proximity ligation assays to detect interactions with MRN complex components

2. Analysis of ATF2 phosphorylation dynamics following DNA damage:

• Western blotting with phospho-specific antibodies following genotoxic treatments

• Time-course analysis to determine kinetics of ATF2 modification

• Pharmacological inhibition of ATM/ATR to determine pathway dependencies

• Mass spectrometry to identify novel damage-induced phosphorylation sites

3. Functional assessment of ATF2 in DNA repair pathways:

• CRISPR/Cas9-mediated knockout or knockin of wild-type versus phospho-mutant ATF2

• Comet assays to quantify DNA damage resolution kinetics

• Homologous recombination and non-homologous end-joining reporter assays

• Cell survival analysis following genotoxic stress

4. Chromatin association studies:

• Chromatin immunoprecipitation to identify damage-responsive target genes

• ChIP-seq analysis to determine genome-wide binding patterns before and after damage

• Fractionation studies to quantify chromatin-bound versus soluble ATF2

The following experimental design table outlines a comprehensive approach:

By implementing these methodological approaches, researchers can comprehensively investigate ATF2's multifunctional role in the DNA damage response, potentially revealing novel therapeutic opportunities in cancer and other diseases associated with genomic instability.

What future directions in ATF2 antibody development would benefit the research community?

The development of next-generation ATF2 antibodies would significantly advance research capabilities across multiple scientific disciplines. Based on current limitations and emerging research needs, several future directions merit consideration:

First, antibodies with enhanced specificity for distinct ATF2 conformational states would enable researchers to distinguish between inactive, DNA-bound, and protein-complexed forms. Such tools would provide unprecedented insights into the dynamic regulation of ATF2 function in different cellular compartments and under various stimulation conditions.

The development of multiplexable antibodies compatible with advanced imaging techniques represents another critical direction. Antibodies optimized for super-resolution microscopy, expansion microscopy, and intravital imaging would allow visualization of ATF2 dynamics in complex cellular environments and living tissues, particularly important for understanding its role in tumor microenvironments.

Additionally, the research community would benefit from antibodies specifically engineered for chromatin immunoprecipitation sequencing (ChIP-seq) applications. Current antibodies often exhibit suboptimal performance in ChIP protocols, limiting genome-wide analyses of ATF2 binding patterns. Antibodies with high affinity under crosslinking conditions and low background would enable more comprehensive mapping of ATF2 transcriptional networks.

The emergence of single-cell proteomics creates demand for antibodies validated for mass cytometry (CyTOF) and single-cell Western blotting. Such tools would allow researchers to examine ATF2 expression and phosphorylation heterogeneity within complex tissues and tumor samples at unprecedented resolution.

Finally, antibodies capable of distinguishing between different ATF2 dimerization partners would address a significant knowledge gap. Given that ATF2's function varies depending on its binding partners (c-Jun, c-Fos, and others), specialized antibodies recognizing specific heterodimeric complexes would illuminate context-dependent regulatory mechanisms and potentially serve as more precise biomarkers for disease states.