SP1L1 Antibody

Overview of SP1 Antibody

SP1 antibodies target the SP1 transcription factor, a protein critical for regulating genes involved in cell growth, apoptosis, and immune responses . These antibodies are primarily used for:

• Immunohistochemistry (IHC)

• Western blotting (WB)

• Immunoprecipitation (IP)

• Chromatin immunoprecipitation (ChIP)

SP1 is a nuclear protein with a molecular weight of ~81 kDa, though observed bands often appear at 90–106 kDa due to post-translational modifications .

Clinical Sensitivity in Breast Cancer

• SP1 vs. 1D5 Antibodies: SP1 (rabbit monoclonal) demonstrates higher sensitivity than the 1D5 clone (mouse monoclonal) in detecting estrogen receptor (ER) in breast cancer. Discrepancy rates range from 8% to 16.9%, with SP1-positive/1D5-negative cases showing survival outcomes similar to double-positive cases .

• Quantitative Performance:

  Parameter	SP1 Antibody	1D5 Antibody
  Signal-to-noise ratio	Higher	Lower
  Discrepant cases	65/73 SP1+/1D5–	8/73 SP1–/1D5+
  Prognostic value	Superior	Inferior

Pan-Cancer Role of SP1

• Elevated SP1 levels correlate with advanced tumor stage, poor prognosis, and immunotherapy response in gastric cancer (GC) .

• Immune Modulation: High SP1 expression associates with CD8+ T cell infiltration and M1 macrophage polarization in GC .

Commonly Used SP1 Antibodies

Staining Protocols

• IHC: Antigen retrieval with EDTA pH 9.0 or citrate buffer pH 6.0 enhances SP1 detection .

• WB: Recommended blocking with 5% non-fat milk to reduce background noise .

Functional Insights

• ER-Beta Cross-Reactivity: SP1 antibodies do not cross-react with ER-beta, ensuring specificity for ER-alpha in breast cancer diagnostics .

• Transcriptional Regulation: SP1 binds GC-rich DNA motifs, modulating genes like PD-L1 and VEGF, which are critical in tumor immune evasion .

Limitations and Considerations

• Background Noise: Higher non-specific binding observed with 1D5 compared to SP1 in IHC .

• Inter-Laboratory Variability: Standardized protocols (e.g., CLIA-certified staining) are essential for consistent SP1 detection .