Granzyme B Granzyme B (OMIM #123910) and perforin (OMIM #170280), proteins released by an effector cell (cytotoxic T cell), can induce apoptosis in target cells by forming transmembrane pores and through cleavage of effector caspases such as caspase-3. In addition, caspase-independent mechanisms of granzyme B-mediated apoptosis have been suggested. Caspase-activated DNAse (CAD) is activated through the cleavage of its associated inhibitor ICAD by caspase-3. CAD is then able to interact with components such as topoisomerase II (Topo II) to condense chromatin, leading to DNA fragmentation and ultimately apoptosis.