APAF1 and neoplasm: The p53-dependent apoptosis pathway is regulated by the p53 protein, which causes mitochondrial release of Cytochrome c, forming apoptosis bodies with Apaf-1 and Pro-Caspase-9, activate Pro-Caspase-9 to form active Caspase-9, and activate effector Caspase-3 through a series of cascade reactions, resulting in tumor cell apoptosis [69].