Anti-Caspase 8 antibodies are directed against the protein encoded by the gene CASP8 in humans. The Caspase 8 protein has an expected mass of 55.4 kDa, but there are 9 reported isoforms. The protein may also be known as MACH, ALPS2B, CAP4, Casp-8, FLICE, FADD-homologous ICE/CED-3-like protease, and FADD-like ICE. Variants of this antigen may also be found in other species, including canine, porcine, monkey, mouse and rat.