Division and apoptosis of E2f-deficient retinal progenitors

The activating E2f transcription factors induce transcription and drive cells out of quiescence, but whether activating E2fs are necessary for normal division is an area of debate. Here, the mouse retina is genetically manipulated to address E2f function in normal cells in vivo. Cells in the mouse retina can still divide in the absence of E2f1–3, although loss of activating E2fs leads to elevated apoptosis; thus, E2fs are not universally required for normal mammalian cell division.