Reactive oxygen species and programmed cell death.

Bcl-2 is a proto-oncoprotein with apparently one function--to suppress programmed cell death (PCD)--yet how it does so remains a mystery. Several authors have proposed that Bcl-2 is an antioxidant that suppresses the formation or action of reactive oxygen species (ROS) and in this way inhibits PCD. However, three recent papers indicate that ROS are not required for PCD and that Bcl-2 can protect against cell death even under conditions where ROS are unlikely to be produced.