Fig. 2

Pathways involved in apoptosis. The intrinsic pathway is activated by various stresses, such as medicine, radiation, and fever. This induces the BCL-2 protein to regulate the permeability of the mitochondrial outer membrane (MOM) and then opens the mitochondrial permeability transition pore. Cytochrome C, via binding to APAF1, causes the formation of the apoptosome, and the procaspase 9 in this process cluster. Caspase 9 proteolytically activates the effector caspases 3 and 7. The extrinsic pathway is death-receptor-induced apoptosis. FAS ligand bind to FAS receptors to activate downstream signaling. This leads to the recruitment of pro-caspase 8, FADD, and TRADD, resulting in the formation of DISC. DISC catalyzes the activation of caspase 8. Caspase 8 directly or indirectly activates caspases 3 and 7. Finally, ApoBDs are formed. Created with BioRender.com