Peer down a microscope to watch cells undergoing programmed cell death and you're in for an awe-inspiring sight. Programmed cell death—or apoptosis as it's also called—unfolds like a well-planned military operation. Within minutes, cells collapse their structural supports, digest and package their contents into membrane-bound parcels, and disappear without a trace into the bowels of scavenger cells. Because apoptosis is key to normal life—in the developing embryo it's needed to cull excess cells, for example, and later in life it eliminates damaged cells—researchers have been working feverishly to piece together the molecular circuitry that underlies this highly choreographed death program.

Within the past few years, however, the apoptosis community has found itself split into two competing camps with divergent views of just what this circuitry looks like. The dispute concerns what role the cell's mitochondria play in apoptosis.