BCL-2, a novel regulator of apoptosis.

The bcl-2 gene has a unique function among mammalian oncogenes as a negative regulator of apoptosis. Its expression pattern in embryonic and adult tissues is consistent with a role in maintaining in vivo survival of specific cell types. The biochemical function of bcl-2 is unknown, but its localization to mitochondrial and microsomal membranes suggests several possibilities. bcl-2 is protective against oxidative stress in mammalian cells and can be replaced by antioxidants in a factor-deprivation model of apoptosis. These results are consistent with a model of apoptotic death involving oxidative stress in a central pathway. The recent discovery of several bcl-2-related genes, some of which also inhibit apoptosis and others that unexpectedly promote apoptosis, has shed new light on several aspects of bcl-2 action.