A potent inhibitor of specific IAPs that binds baculovirus IAP repeat (BIR) domains (Kis = 28, 14, 17, and 43 nM for XIAP BIR3, NL-IAP BIR, BIRC2 (c-IAP1) BIR3, and BIRC3 (c-IAP2) BIR3, respectively); induces activation of caspases, decreasing the viability of cancer cells without affecting normal cells.