Activated caspases are the enzymes responsible for the initiation of apoptosis; the caspases hydrolyze a large quantity of structural proteins and protein enzymes. Caspases are stored in cells as inactive precursors and require cleavage to produce the active form of the enzyme. These enzymes contain one N-terminal prodomain, a large subunit and a small subunit which brings about the active enzymes following the initiation apoptosis.