Figure 2.

Two apoptotic pathways are demonstrated. Extrinsic pathway which is triggered through death receptors and intrinsic one which is caused by mitochondrial alterations. In the extrinsic pathway, binding death ligands to their receptors mainly CD95 (Fas), TNFR1, and TRAIL triggers death signal through Fas-associated death domain (FADD) which then activates caspase-8. In the intrinsic pathway, cytochrome C (Cyt-C) is released from the mitochondria and form apoptosome complex after attaching to apoptotic protease activating factor-1 (Apaf-1) followed by activating caspase-9. The activated caspase-8 and 9 (initiator) activate the effector caspases 3, 6, and 7 which then results in cell death characterized by obvious morphological and biochemical alterations. Furthermore, cell death depends on amounts of various members of Bcl2 family. For more information, read the text.