Fig. 1.

Apoptotic signaling pathway. Caspase-8 is activated via the extrinsic signaling pathway by the binding of a ligand to the death receptor. The intrinsic signaling pathway is activated by changes in the mitochondrial membrane potential and the subsequent release of cytochrome C, which influences the pro-apoptotic factors BAK, Bad, and BAX as well as the anti-apoptotic factors Bcl2 and Bcl-xl and thus triggers caspase-9. Both pathways merge into a common pathway, in which effector caspase-3 finally induces apoptosis