BIRC2 and cancer: To date, eight human IAPs have been characterized.1 Dysregulation of the IAPs has been observed in multiple cancer cell lines and tumor samples and has been suggested as contributing to chemoresistance and treatment failure.2–5 The two cellular IAPs (cIAP1 and cIAP2) contain three N-terminal BIR domains, that is, BIR1, BIR2 and baculovirus IAP protein repeat 3 (BIR3), and a C-terminal really interesting new gene (RING) domain with E3 ubiquitin ligase activity.6–8 The distinct BIR domains of cIAP1 and cIAP2 facilitate specific and unique interactions with other proteins.