Pro apoptotic proteins function by activating the intrinsic or extrinsic apoptotic pathways. The intrinsic pathway is mitochondria-mediated and is regulated by the B-cell lymphoma 2 (Bcl-2) family of proteins. This family includes both pro apoptotic and anti apoptotic members. Pro apoptotic proteins such as Bax and Bak promote the release of cytochrome c from the mitochondria, leading to the activation of caspases which execute the cell death program. The extrinsic pathway is initiated by the binding of death ligands to their corresponding death receptors on the cell surface, subsequently leading to caspase activation.
