E2F1 and cancer: In cancer cells Apaf-1 transcription is controlled by E2F-1 (Furukawa et al., 2002) and by TP53 (Rozenfeld-Granot et al., 2002), so the decrease in E2F-1 that accompanies exit from the cell cycle and that precedes differentiation may provide a straight forward explanation for a decrease in Apaf-1 that limits caspase activation during differentiation.