Anti-E(spI) antibodies are used in antigen-specific immunodetection in biological samples. The target E(spI) is a known alias name of the protein TLE family member 4, transcriptional corepressor, encoded by the TLE4 gene in humans. This 773-amino acid residue protein is reported to be a transcriptional corepressor that binds to a number of transcription factors. It is localized to the nucleus of the cell and features ubiquitinated and phosphorylated post-translational modifications. Other synonyms for E(spI) include BCE-1, BCE1, and E(spI).