Figure 4

Programmed cell death type I: Apoptosis: In response to cellular damage, activation of p53 results in increased expression of Bax and antagonism of the anti-apoptotic protein Bcl-2. As a result, mitochondrial membrane permeability increases and cytochrome C is released into the cytosol. Cytochrome C binds Apaf-1 to form an apoptosome complex leading to activation of caspase-9 and initiation of the caspase cascade and resultant cell death.