Caspase-10 is a DED (death effector domain)-containing caspase and functions as an initiator caspase in Fas/TNF induced apoptosis (1). Four isoforms of caspase-10 have been identified: caspase-10a (Mch4), caspase-10b (FLICE2), caspase-10c and caspase-10d. They have the same prodomain but different mature large and small subdomains (2-4). Upon death ligand-receptor binding, caspase-10 is coupled to the multimeric Fas/TNF receptor complex via DED/FADD adaptor interaction (1-4). This complex processes procaspase-10 into a large active fragment and a small fragment. Cleaved caspase-10 further processes other caspase members, including caspase-3 and caspase-7, to initiate a caspase cascade, leading to apoptosis (3-6).