Figure 1: Cellular processes: apoptosis, autophagy, and cellular senescence are distinct cellular response to stress. Autophagy and apoptosis are induced in response to awide variety of stresses. There are many purposes for autophagy that include the quality control of protein and organelle, damage mitigation, and energy homeostasis. Stressed cells activate autophagy, which prevents damage and maintains metabolism though lysosomal turnover of cellular components. Autophagy can facilitate senescence or limit damage and delay apoptosis to allow recovery of normal cell function.