Molecular mechanisms of E2F-dependent activation and pRB-mediated repression

Alterations in transcription of genes regulated by members of the E2F family of transcription factors can be viewed as a measure of the ebb and flow in a constantly evolving battle between repressor and activator complexes. Various chromatin regulatory complexes have been linked to Rb/E2F proteins, and changes in histone modifications correlate with states of E2F-dependent transcription. E2F has traditionally been viewed in the context of cell-cycle control. However, several recent studies have revealed a new aspect of E2F function in which pRB/E2F-family proteins confer stable repression of transcription. Such repression is evident in both actively proliferating cells and in cells that have withdrawn from the cell cycle.