Apoptotic regulator capable of exerting proapoptotic and anti-apoptotic activities and plays crucial roles in apoptosis, cell proliferation, and cell cycle control (PubMed:11024045, PubMed:11084335, PubMed:11162435, PubMed:16729033, PubMed:17294084). Its anti-apoptotic activity is mediated through the inhibition of CASP3, CASP7 and CASP9, as well as by its E3 ubiquitin-protein ligase activity (PubMed:11024045, PubMed:16729033). As it is a weak caspase inhibitor, its anti-apoptotic activity is thought to be due to its ability to ubiquitinate DIABLO/SMAC targeting it for degradation thereby promoting cell survival (PubMed:16729033). May contribute to caspase inhibition, by blocking the ability of DIABLO/SMAC to disrupt XIAP/BIRC4-caspase interactions (PubMed:16729033). Protects against apoptosis induced by TNF or by chemical agents such as adriamycin, etoposide or staurosporine (PubMed:11084335, PubMed:11162435, PubMed:11865055). Suppression of apoptosis is mediated by activation of MAPK8/JNK1, and possibly also of MAPK9/JNK2 (PubMed:11865055). This activation depends on TAB1 and MAP3K7/TAK1 (PubMed:11865055). In vitro, inhibits CASP3 and proteolytic activation of pro-CASP9 (PubMed:11024045). {ECO:0000269|PubMed:11024045, ECO:0000269|PubMed:11084335, ECO:0000269|PubMed:11162435, ECO:0000269|PubMed:11865055, ECO:0000269|PubMed:16729033, ECO:0000269|PubMed:17294084}. [Isoform 1]: Blocks staurosporine-induced apoptosis (PubMed:11322947). Promotes natural killer (NK) cell-mediated killing (PubMed:18034418). {ECO:0000269|PubMed:11322947, ECO:0000269|PubMed:18034418}. [Isoform 2]: Blocks etoposide-induced apoptosis (PubMed:11162435, PubMed:11322947). Protects against natural killer (NK) cell-mediated killing (PubMed:18034418). {ECO:0000269|PubMed:11162435, ECO:0000269|PubMed:11322947, ECO:0000269|PubMed:18034418}. This is the function of ENSG00000101197 (BIRC7, baculoviral IAP repeat containing 7).