Acciones bioquímicas o fisiológicas
E2F was originally identified as a transcription factor mediating the transcription of adenovirus E2 gene. It is a heterodimer composed of two structurally related subunits, termed E2F and DP. E2F is encoded by at least five genes, E2F-1 through E2F-5, and DP is encoded by at least two genes, DP-1 and DP-2. All these genes (E2F-1 through E2F-5, DP-1 and DP-2) have been considered as members of the E2F gene family because they have a number of common structural and functional characteristics. Among those members of the E2F family, E2F-1 was the first E2F gene cloned and characterized. The E2F-1 protein has been shown to interact with RB both in vitro and in vivo. Although the E2F proteins can function as transcription factors by themselves, they should be considered as RB-mediators as well because almost every functional response of RB protein(s) requires the presence of E2F protein(s).