The Inhibitor of apoptosis or IAP family is a group of eight structurally related proteins: XIAP (BIRC4), cIAP1 (BIRC2), cIAP2 (BIRC3), NAIP (BIRC1), Survivin (BIRC5), BIRC6, Livin (BIRC7), and BIRC8. All feature an 80-amino acid long BIR (baculovirus IAP repeat) domain that was first discovered from the baculoviral ability to suppress host cell death response. It is now known that the IAP family members inhibit apoptosis by directly binding and inhibiting caspases or by ubiquitinating the pro-apoptotic kinase RIP1. There is considerable clinical significance for the IAP proteins due to their anti-apoptotic ability and other roles in signaling pathways. IAPs are often found to be overexpressed in various cancers, as well as other studies that link involvement in immune responses and inflammation.