Caspase-9 (ICE-LAP6, Mch6) is an important member of the cysteine aspartic acid protease (caspase) family. Upon apoptotic stimulation, cytochrome c released from mitochondria associates with the 47 kDa procaspase-9/Apaf-1. Apaf-1 mediated activation of caspase-9 involves intrinsic proteolytic processing resulting in cleavage at Asp315 and producing a p35 subunit. Another cleavage occurs at Asp330 producing a p37 subunit that can serve to amplify the apoptotic response. Cleaved caspase-9 further processes other caspase members, including caspase-3 and caspase-7, to initiate a caspase cascade, which leads to apoptosis.