Cheson Figure 8 (Klasa et al).
In order for the cell to move from the G1 to the S phase of the cycle, the cell passes the restriction point, the G1 checkpoint.
This process requires phosphorylation of the Rb protein by cdks. The E2F transcription factor dissociates from the Rb protein complex releasing the phosphorylated Rb. E2F facilitates progression by initiating the transcription of the cell cycle control genes. Overexpression of cyclin D has been implicated in the pathogenesis of mantle cell lymphoma by enhancing the transition through G1 to S.
