Apoptosis is a common mode of programmed cell death occurring during d
evelopment as well as in many pathological conditions, in which the ce
ll plays an active role in its own demise. Although the morphological
and biochemical hallmarks of apoptosis are conserved across phyla and
cell type, the mechanism(s) of apoptosis is unknown. However, data rec
ently published demonstrate that expression of the anti-apoptotic gene
bcl-2 decreases the net cellular generation of reactive oxygen specie
s, and that reactive oxygen species serve as mediators of apoptosis in
at least some cases.