Figure 4.

Combinatorial control of gene expression by Rb/E2F with other transcription factors. Owing to specific interactions with other transcription factors, individual members of the Rb and E2F families can differentially regulate specific target genes. As shown in the repression model, specific Rb/E2F complexes may be preferentially recruited to an E2F-binding site based on the ability of Rb and/or E2F to bind to another transcription factor with an adjacent binding site. Similarly, in the activation model, the ability of individual E2F family members to bind to other transcription factors may preferentially recruit both activators to promoters containing adjacent binding sites, synergistically activating transcription.