Activation of the intrinsic pathway begins with cellular stress that results in mitochondrial dysfunction. This can be due to toxic exposure to chemicals, radiation, or other environmental factors that cause damage to mitochondria. The key regulators of this pathway are the Bcl-2 family proteins, which include both pro-apoptotic and anti-apoptotic members. Upon activation by stress signals, pro-apoptotic proteins such as Bax and Bak cause MOMP, allowing cytochrome c and other apoptogenic factors to escape into the cytosol.
