What are the common stimuli for apoptosis?

Common stimuli for apoptosis include: pH, radiation, infection, oxygen concentration, cytokines and heat. Studies have shown that a low extracellular pH encourages the induction of apoptosis. Radiation kills cells as an immediate consequence of radiation damage and usually die in interphase within a few hours. Cells initiate apoptosis in response to viral infections, with a reduction in the release of progeny virus. During anoxia, oxygen levels decrease to at or below 0.5%, as most cells will induce apoptosis. Cytokines and their receptors are crucial regulators of apoptosis. Heat causes an increase in cellular temperature and thus induces protein denaturation and disrupts cellular processes resulting in apoptosis.