Apoptosis, an active process of cellular self-destruction involved in a variety of physiological and pathological conditions, can be induced by either oxidants or stimulators of cellular oxidative stress. Mild damages such as ionizing and ultraviolet radiation, hyperoxia,hyperthermia, infection etc, will injure the cell via reactive oxygen species (ROS), which may either react with the polyunsaturated fatty acids,leading to the formation of oxidized lipids, or activate certain genes related to cell death. As a result, the cell commits suicide following a sequence of biochemical change. bcl-2, one of the proto-oncogenes, was found to play a role in the regulation of apoptosis.