COBRA1 (cofactor of BRCA1) also known as NELF-B, is an essential component of the negative elongation factor (NELF) complex. COBRA1 has been shown to directly bind estrogen receptor alpha (ERα) and repress ERα-mediated transcription (Aiyar SE et al., 2004). COBRA1 has also been demonstrated to interact with c-Jun and c-Fos suggesting a role in modulation of the AP-1 pathway and therefore may be important in cell proliferation, differentiation, apoptosis and oncogeneis (Zhong H et al., 2004).Synonyms: COBRA1, Cofactor of BRCA1, KIAA1182, NELFB, Negative elongation factor B