The intrinsic pathway is typically initiated by various intracellular stress signals such as DNA damage, oxidative stress, and other forms of cellular injury. These stress signals lead to the activation of pro-apoptotic members of the Bcl-2 family of proteins, such as Bax and Bak. These proteins translocate to the mitochondria, where they promote the release of cytochrome c from the intermembrane space into the cytosol.
