Caspase 3 is a member of the CED-3 subfamily of caspases and is responsible for the cleavage of many key proteins such as the nuclear enzyme poly(ADP-ribose) polymerase (PARP), the inhibitor of caspase-activated deoxyribonuclease (ICAD), and gelsolin, a protein involved in apoptosis regulation. Caspase?3 is considered to be an effector caspase, activating pro-caspase?6 and pro-caspase?9 in vitro. Caspase 3 can be activated by caspase 8, caspase 6, and granzyme B.