Livin is a novel member in the IAP (inhibitor of apoptosis) protein family. Livin contains a single baculoviral IAP repeat (BIR) domain and a RING finger domain and has two isoforms termed Livin-α and Livin-β. Transfection of Livin protected cells from apoptosis induced by FADD, BAX, RIP, RIP3 and DR6. Livin directly reacts with several caspases including Caspase-3, -7, and –9, and it inhibits the activation of caspase-9 induced by Apaf-1, cytochrome c and ATP.