CENTRAL ROLE OF MITOCHONDRIA. “These later examples…clearly demonstrates the central role of the mitochondria in the highly regulated and complex process of many forms of programmed cell death. The activation of the mitochondrial pathway can also occur following the activation of the extrinsic pathway.” Mitochondria were engulfed bacteria early in evolution.
http://www.sciencedirect.com/science/article/pii/S0167488910002764