LIPG Antibody
Description
Definition and Mechanism of LIPG Antibody
LIPG antibodies are immunoglobulins designed to bind specifically to the endothelial lipase protein (LIPG), enabling its detection and quantification in biological samples. These antibodies are categorized into monoclonal and polyclonal types, each with distinct advantages:
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Monoclonal antibodies (e.g., GTX84193 from GeneTex ): High specificity, reproducibility, and suitability for techniques like immunoprecipitation (IP) and flow cytometry (FACS).
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Polyclonal antibodies (e.g., PA1-16799 from Thermo Fisher ): Broad epitope recognition, ideal for Western blot (WB) and immunohistochemistry (IHC).
LIPG antibodies are used to study LIPG’s enzymatic and non-enzymatic roles, including HDL metabolism, cytokine regulation, and cancer-related signaling pathways .
Types of LIPG Antibodies and Their Applications
Applications:
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Western Blot (WB): Quantifies LIPG protein levels, as demonstrated in breast cancer cell lines (e.g., MCF7-LIPG) .
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Immunohistochemistry (IHC): Evaluates LIPG expression in tumor tissues (e.g., TNBC and LUAD) .
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Immunoprecipitation (IP): Identifies LIPG protein-protein interactions, such as its association with DTX3L in ISGylation pathways .
Research Findings on LIPG’s Role in Cancer
LIPG antibodies have enabled critical insights into LIPG’s oncogenic functions:
Breast Cancer (TNBC)
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Expression: LIPG mRNA and protein levels are significantly elevated in triple-negative breast cancers (TNBCs) compared to luminal subtypes .
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Functional Impact: LIPG knockdown reduces cell proliferation, migration, and cancer stem cell (CSC) sphere formation in TNBC cell lines (e.g., MCF10DCIS) .
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Mechanisms: LIPG promotes basal/epithelial-mesenchymal transition (EMT) and interferes with DTX3L-ISG15 signaling, enhancing tumor aggressiveness .
Lung Adenocarcinoma (LUAD)
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Prognostic Biomarker: High LIPG expression correlates with poor prognosis, lymph node metastasis, and advanced tumor stages .
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Immune Microenvironment: LIPG expression is linked to immune checkpoint genes (e.g., PD-1, CTLA-4) and immune cell infiltration (e.g., activated memory CD4+ T cells) .
Prognostic Value
| Cancer Type | LIPG Expression | Outcome | Source |
|---|---|---|---|
| TNBC | High | Poor survival, enhanced metastasis | |
| LUAD | High | Poor prognosis, drug resistance | |
| Luminal A BC | High | Elevated breast cancer risk (HER2-negative) |
Therapeutic Implications
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Targeting LIPG: Inhibitors like XEN445 suppress tumor formation by blocking LIPG’s enzymatic activity, reducing HDL cholesterol and altering lipid metabolism .
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Immune Modulation: LIPG antibodies may aid in monitoring immune checkpoint inhibitor responses, given its association with T cell infiltration .
Antibody Specificity and Sensitivity
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Cross-Reactivity: Polyclonal antibodies may recognize non-specific epitopes, requiring validation (e.g., using negative controls with non-specific serum ).
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Detection Range: Commercial ELISA kits vary in sensitivity (e.g., 0.031–420 ng/ml), necessitating standardized protocols .
Dual Functional Roles of LIPG
Product Specs
Constituents: 50% Glycerol, 0.01M PBS, pH 7.4
Target Background
- A study examining the correlation between the LIPG polymorphism (584 C/T) and coronary artery disease (CAD) in Turkish individuals revealed that the CC genotype may be a genetic risk factor for CAD, while carrying the T allele might offer protection against CAD. PMID: 30150432
- Research identified a missense Asn396Ser mutation (rs77960347) in the endothelial lipase (LIPG) gene, with an allele frequency of 1% in the general population. This mutation was significantly associated with depressive symptoms (P-value=5.2 x 10-08, beta=7.2). PMID: 27431295
- The EL 2237 A allele may be linked to elevated Apo A1 levels in individuals with Coronary Artery Disease. PMID: 27612170
- Elevated hepatic expression of endothelial lipase effectively mitigates cholesterol diet-induced hypercholesterolemia and safeguards against atherosclerosis. PMID: 28546217
- Endothelial lipase is upregulated in human umbilical vein endothelial cells by interleukin-6, partly through the p38 MAPK and p65 NF-kappaB signaling pathways. PMID: 27430252
- Endothelial lipase (EL) 2037T/C and 2237 G/A polymorphisms may not impact the lipid-lowering effects of rosuvastatin in Chinese coronary artery disease patients. PMID: 27600285
- Endothelial lipase protein expression was found to be increased in the skeletal muscle of middle-aged men with high oxygen consumption. PMID: 26447519
- LIPG polymorphisms have been associated with hyperlipidemia. PMID: 27590083
- FoxA1, FoxA2, and LIPG regulate the uptake of extracellular lipids for breast cancer growth. PMID: 27045898
- Research suggests that the SNP -384A/C in the LIPG gene may be associated with the risk of coronary artery disease (CAD) in the Han Chinese population, implying a potential role of the LIPG gene in CAD development. PMID: 26124511
- A study investigated whether a specific variant of the endothelial lipase gene was more closely linked to the severity of diabetic retinopathy. PMID: 24852509
- Several lipid-related gene polymorphisms interact with overweight/obesity to influence blood pressure levels. PMID: 23109900
- The EL-384A/C polymorphism was found to be significantly associated with acute coronary syndrome (ACS) and lipid profiles in an elderly Uygur population in Xinjiang. PMID: 25291260
- Studies revealed that angiotensin II (AngII) increased the protein levels of endothelial lipase (EL), NF-kappaB p65, MAPK p38, and the proliferation of umbilical vein endothelial cells (HUVECs). PMID: 25250890
- Genetic investigations of patients with early-onset coronary artery disease (CAD) in the Chinese Han population indicate that the EL 584C/T variant is not consistently involved in the pathogenesis of early-onset CAD. PMID: 24634127
- A meta-analysis suggests that carriers of the EL 584 T allele exhibit higher HDL-C levels in Caucasian populations. However, it may not serve as a protective factor against coronary heart disease (CHD). PMID: 24886585
- Research indicates the presence of the spatial consensus catalytic triad "Ser-Asp-His", a characteristic motif found in lipoprotein lipase, hepatic lipase, and endothelial lipase. PMID: 23991054
- EL activity was observed to be higher in individuals with metabolic syndrome and obesity. It exhibited a negative association with high-density lipoprotein-cholesterol and apolipoprotein A-I in control and metabolic syndrome groups, respectively. PMID: 24458708
- The T allele of the LIPG -584C/T polymorphism might play a potential role in the susceptibility to atherogenesis in the Turkish population. PMID: 23673478
- Interleukin-6 stimulates the translocation of HDL through the endothelium, the initial step in the reverse cholesterol transport pathway, by enhancing EL expression. PMID: 24115033
- Individuals with a complete loss-of-function mutation of LIPG displayed higher plasma high-density cholesterol levels compared to carriers of partial loss-of-function mutations. PMID: 23243195
- The EL -384A/C gene polymorphism might be associated with ACS in the Chinese Han population, suggesting a potential role of this variant in the pathogenesis of ACS. PMID: 22723003
- Urinary endothelial lipase is a highly accurate gastric cancer biomarker, potentially applicable for general screening with high sensitivity and specificity. PMID: 23510199
- Endothelial lipase supplies cells with free fatty acids and HDL-derived lysophosphatidylcholine and lysophosphatidylethanolamine species, leading to increased cellular triglycerides and phosphatidylcholine (PC) content and decreased PC synthesis. PMID: 23075452
- EL expression modulates vascular remodeling as well as plasma HDL-C levels. PMID: 22972429
- Starvation regulates endothelial lipase expression through SREBP-2. PMID: 23102786
- Analysis of LIPG, CETP, and GALNT2 mutations in Caucasian families with exceptionally high HDL cholesterol was conducted. PMID: 22952570
- A study tested the hypothesis that placental EL expression is affected by obesity during pregnancy and gestational diabetes. Metabolic inflammation with high leptin and increased TNF-alpha concentration at the fetal-placental interface regulates placental EL expression. PMID: 21852675
- Endothelial lipase plays a role in thyroid and adipocyte biology, in addition to its well-established role in endothelial function and HDL metabolism. PMID: 22740344
- Common and rare genetic variants in CETP and LIPC, but not LIPG, were more frequently observed in the Thai HALP group, potentially contributing to high high-density lipoprotein cholesterol phenotypes in this population. PMID: 22464213
- A reduction in nascent HDL formation may partly explain the decrease in HDL-C during inflammation, as both EL and SAA are known to be upregulated. PMID: 21957202
- Research revealed that a common nonfunctional coding variant associated with HDL-C (rs2000813) is in linkage disequilibrium with a 5' UTR variant (rs34474737) that reduces LIPG promoter activity. PMID: 22174694
- Treatment of patients with coronary artery disease with lipid-modulating and/or antiplatelet drugs may significantly decrease endothelial lipase expression. PMID: 21122200
- Findings indicate that individuals with the TT endothelial lipase genotype experience greater benefits from alcohol consumption compared to those with CT and CC genotypes in terms of increasing serum high-density lipoprotein cholesterol and apolipoprotein (Apo) AI levels. PMID: 21816559
- The c.584C>T EL polymorphism is linked to a higher risk of diabetic retinopathy, potentially associated with alterations in HDL-cholesterol metabolism and blood pressure levels. PMID: 21145773
- Endothelial lipase and EL-generated lysophosphatidylcholines promote endothelial IL-8 synthesis. PMID: 21130993
- Sulforaphane inhibits endothelial lipase expression by inhibiting NF-kappaB, which may have a beneficial effect on HDL cholesterol levels. PMID: 20688330
- The LIPG 584T allele is associated with elevated serum HDL-C, TC, and ApoB levels. PMID: 20923576
- Common genetic variation in endothelial lipase (LIPG) does not appear to play a role in the risk of coronary artery disease and deep venous thrombosis. PMID: 20466371
- Statins can reduce EL expression in vitro and in vivo by inhibiting RhoA activity. The inhibition of EL expression in the vessel wall may contribute to the anti-atherogenic effects of statins. PMID: 20045866
- LPL and LIPG have been reported in the human testis and in germ cell neoplasms. PMID: 19780863
- It appears that plasma endothelial lipase levels in individuals with atherosclerosis may be higher than those measured in healthy individuals. [review] PMID: 20621031
- This N-terminal variant leads to reduced secretion of endothelial lipase, potentially resulting in increased HDL-C levels. PMID: 19411705
- EDL mediates both HDL binding and uptake, and the selective uptake of HDL-CE, independently of lipolysis and CLA-1. PMID: 12164779
- Endothelial lipase plays a role in HDL metabolism [review] PMID: 12569156
- EL is a major determinant of HDL concentration in humans. PMID: 12601178
- Expression of human endothelial lipase in mice results in a dose-dependent increase in postheparin plasma phospholipase activity, catabolic rate of HDL-apolipoprotein, and uptake of apoA-I in both kidney and liver. PMID: 14517167
- Hepatic expression of human EL in mice resulted in markedly decreased levels of VLDL/LDL cholesterol, phospholipid, and apoB, accompanied by significantly increased LDL apolipoprotein and phospholipid catabolism. PMID: 15117821
- N-linked glycosylation plays a role in the secretion and activity of endothelial lipase. PMID: 15342690
- Findings suggest that endothelial lipase (EL) on the endothelial cell surface can promote monocyte adhesion to the vascular endothelium through its interaction with heparan sulfate proteoglycans. PMID: 15485805
Q&A
What is LIPG and how does it differ from other lipases?
LIPG (endothelial lipase) is a key enzyme involved in lipid metabolism that differs structurally and functionally from lipoprotein lipase (LPL). While LPL primarily functions as a triglyceride lipase with minimal phospholipase activity, LIPG has distinct enzymatic properties and tissue expression patterns . LPL catalyzes the hydrolysis of triglycerides from circulating chylomicrons and very low-density lipoproteins (VLDL), playing an important role in lipid clearance from the bloodstream, utilization, and storage . LIPG has been specifically implicated in tumor development processes, particularly in triple-negative breast cancer (TNBC), where it shows aberrant overexpression compared to normal breast tissue .
What are the primary applications for LIPG antibodies in basic research?
LIPG antibodies serve multiple purposes in basic research, including:
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Protein detection via western blotting (identifying both 68 kDa glycosylated full-length LIPG and 40 kDa cleaved LIPG protein)
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Tissue expression analysis through immunohistochemistry (IHC)
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Quantitative analysis of expression levels via H-score analysis
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Cell-type identification in flow cytometry
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Subcellular localization studies using immunofluorescence
When selecting LIPG antibodies, researchers should consider the specific application, as different clones may perform optimally in different contexts . For instance, IHC applications may require antibodies optimized for formalin-fixed, paraffin-embedded tissues, while flow cytometry applications require antibodies that recognize native protein conformations .
How should researchers validate LIPG antibody specificity?
Validation of LIPG antibody specificity requires a multi-faceted approach:
| Validation Method | Implementation | Purpose |
|---|---|---|
| Positive controls | Use known LIPG-expressing cell lines (e.g., MCF10DCIS, MDA-MB-468) | Confirm antibody binding to endogenous LIPG |
| Negative controls | Use cell lines with low LIPG expression (e.g., MCF7, T47D) | Confirm absence of non-specific binding |
| Knockdown validation | Use siRNA to suppress LIPG expression | Confirm signal reduction correlates with knockdown |
| Overexpression validation | Use LIPG-overexpressing cell line (e.g., MCF7-LIPG) | Confirm signal increase with protein expression |
| Western blot analysis | Look for bands at expected molecular weights (68 kDa and 40 kDa) | Verify antibody recognizes target protein forms |
Researchers should be particularly careful to distinguish between LIPG and other lipases like LPL which share some structural similarities . Cross-reactivity testing against related lipases is essential for confirming antibody specificity.
What are the optimal conditions for LIPG antibody use in immunohistochemistry?
For optimal results in IHC applications with LIPG antibodies, researchers should:
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Perform antigen retrieval optimization (typically heat-induced epitope retrieval in citrate buffer)
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Establish appropriate antibody dilution through titration experiments (typically starting with manufacturer's recommendations)
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Include positive controls (e.g., TNBC samples) and negative controls (e.g., antibody diluent only)
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Develop consistent scoring methods (e.g., H-score analysis as used in studies examining LIPG expression in breast cancer tissues)
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Use tissue microarrays when comparing expression across multiple samples to minimize batch effects
Research has shown that when optimized, LIPG antibodies can effectively discriminate between breast cancer subtypes, with higher expression in triple-negative breast cancers compared to luminal breast cancers .
How can LIPG antibodies be used to investigate the role of LIPG in cancer progression?
LIPG antibodies are invaluable tools for elucidating LIPG's role in cancer:
What methods can be used to distinguish between different forms of LIPG protein?
LIPG exists in multiple forms that can be distinguished using specific antibody-based approaches:
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Western blot analysis: The glycosylated full-length LIPG protein appears at 68 kDa while the cleaved LIPG protein appears at 40 kDa on western blots . Different breast cancer cell lines show varying expression patterns of these forms; for example, high 68 kDa LIPG expression was detected in TNBC cell lines but not in LuBC cell lines, while high 40 kDa LIPG expression was specifically detected in Hs578T cells .
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Glycosylation-specific detection: Using enzymes like PNGase F to remove N-linked glycans before western blotting can help confirm glycosylation status.
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Domain-specific antibodies: Antibodies targeting different domains of LIPG can be used to differentiate between full-length and cleaved forms.
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Subcellular fractionation: Combined with western blotting, this approach can determine the localization patterns of different LIPG forms.
Understanding the predominant form of LIPG in specific cell types is critical, as research indicates that the glycosylated, full-length 68 kDa LIPG protein is the predominant form expressed in TNBC cell lines, which may have functional implications for its role in cancer progression .
What are common issues with LIPG antibody staining in IHC and how can they be resolved?
| Issue | Possible Causes | Solutions |
|---|---|---|
| Weak or absent staining | Insufficient antigen retrieval, Low antibody concentration, Low LIPG expression | Optimize antigen retrieval conditions, Increase antibody concentration, Use amplification systems, Include positive controls |
| High background | Non-specific binding, Excessive antibody concentration, Inadequate blocking | Increase blocking time/concentration, Optimize antibody dilution, Include additional washing steps, Use species-matched secondary antibodies |
| Variable staining intensity | Tissue processing differences, Fixation inconsistencies | Standardize fixation protocols, Use automated staining platforms, Develop quantitative scoring methods (e.g., H-score) |
| False positives | Cross-reactivity with related lipases | Use well-characterized antibodies, Include appropriate controls, Confirm with alternative detection methods |
When analyzing breast cancer tissues, researchers should be aware that LIPG protein can be detected at different levels in TNBCs compared to LuBCs, and quantification through H-score analysis can help standardize these comparisons .
How can researchers optimize LIPG detection in western blotting?
For optimal western blot detection of LIPG:
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Sample preparation: Use appropriate lysis buffers containing protease inhibitors to prevent degradation of LIPG.
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Gel selection: Use 8-10% gels to achieve good separation of the 68 kDa and 40 kDa LIPG forms.
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Transfer conditions: Optimize transfer time and voltage for high molecular weight proteins.
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Blocking: Use 5% non-fat dry milk or BSA in TBST for reducing non-specific binding.
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Antibody incubation: Optimize primary antibody concentration and incubation time (typically 1:500-1:2000 dilution and overnight at 4°C).
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Controls: Include positive controls like MCF10DCIS or MDA-MB-468 cell lysates (high 68 kDa LIPG) and negative controls like T47D or MCF7 cell lysates (low LIPG) .
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Detection system: Use enhanced chemiluminescence with exposure time optimization.
When analyzing LIPG expression in different breast cancer cell lines, researchers should expect to detect the glycosylated full-length 68 kDa LIPG in TNBC cell lines (MCF10DCIS, MDA-MB-231, MDA-MB-468, Hs578T) but not in LuBC cell lines (T47D, MCF7), while the 40 kDa cleaved form might be specifically detected in certain cell lines like Hs578T .
How can LIPG antibodies be employed in functional studies of cancer cell behavior?
LIPG antibodies can be utilized in combination with various functional assays to assess the role of LIPG in cancer:
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Knockdown validation: LIPG antibodies are essential for confirming protein reduction following siRNA treatment, as demonstrated in studies with MCF10DCIS and MDA-MB-468 cell lines .
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Phenotypic assays: After confirming LIPG knockdown using antibodies, researchers can assess changes in:
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Cell growth and proliferation
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Migration and invasion capacity
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Cancer stem cell (CSC) sphere formation
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EMT marker expression (E-cadherin, vimentin)
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Mechanism investigation: LIPG antibodies can help correlate LIPG expression with downstream molecular changes, such as alterations in stem-cell and basal/EMT programming genes .
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In vivo studies: LIPG antibodies can be used to confirm LIPG expression in xenograft models, correlating expression with tumorigenicity and metastatic potential.
Research has shown that LIPG knockdown in MCF10DCIS cells markedly suppresses cell growth, migration, invasion, and CSC sphere formation, indicating that LIPG expression is required for tumorigenic, basal-like, and EMT characteristics of these cells .
What considerations are important when using LIPG antibodies for co-immunoprecipitation studies?
When using LIPG antibodies for co-immunoprecipitation (co-IP) to identify LIPG-interacting proteins:
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Antibody selection: Choose antibodies that recognize native, non-denatured LIPG protein.
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Cross-linking considerations: Determine whether chemical cross-linking is needed to stabilize transient protein-protein interactions.
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Lysis conditions: Use mild lysis buffers to preserve protein-protein interactions while still effectively extracting LIPG.
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Pre-clearing step: Include pre-clearing with non-specific IgG to reduce non-specific binding.
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Controls:
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Negative control: IgG from the same species as the LIPG antibody
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Input control: A portion of the lysate before immunoprecipitation
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Knockdown control: Lysate from LIPG-knockdown cells
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Validation: Confirm successful immunoprecipitation by western blotting for LIPG in the IP fraction.
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Detection methods: Consider mass spectrometry for unbiased identification of co-precipitated proteins or western blotting for specific candidate interactors.
Co-IP studies can help reveal potential binding partners of LIPG that may contribute to its role in cancer progression, providing mechanistic insights beyond expression analysis.
