ESR1 and breast neoplasm: Finally, NCOA3 (AIB1) is amplified in 11% of breast tumors and is associated with a worse prognosis in ER+, but also ER− tumors (Burandt et al. 2013); its tumorigenic potential may therefore result from a role as coactivator of other transcription factors, such as E2F1 (Louie et al. 2004).