Early 2 Factor (E2F) 

The Early 2 Factors (E2Fs) are a family of eight winged-helix transcription factors that are key to regulating cell cycle progression from G1 to S phase among other functions. E2F1, E2F2, and E2F3a are expressed in early G1 through S phase and are believed to promote S phase initiation by activating genes involved in the G1 to S phase transition18. E2F3b, E2F4, E2F6, E2F5, E2F7, and E2F8 act as repressors and are expressed later in the cell cycle. E2Fs participate in myriad cell biological processes including: the cell cycle, DNA repair, apoptosis, development, differentiation, and metabolism.