Apoptosis has gained central importance in the study of many biological processes, including neoplasia, neurodegenerative diseases and development. The proteases that mediate apoptosis are called caspases (cysteinyl-aspartic acid proteases). Cleaved caspase-3 antibody detects endogenous levels of the large fragment of activated caspase-3, a protease that mediates apoptosis. Activation of caspase-3 requires proteolytic processing of its inactive zymogen into activated p17 and p12 subunits. Cleavage of caspase-3 requires aspartic acid at the P1 position. This antibody does not cross-react with other cleaved caspases.