G0 and Early G1

In G0 and early G1 in quiescent cells, p130 (RBL2) bound to E2F4 or E2F5 and either DP1 or DP2, associates with the MuvB complex, forming an evolutionarily conserved DREAM complex, that represses transcription of cell cycle genes. During early G1 phase in actively cycling cells, p107 (RBL1) forms a complex with E2F4 and DP1 or DP2 and represses transcription of E2F target genes. Both p130 (RBL2) and p107 (RBL1) repress transcription of E2F targets through recruiting histone deacetylase HDAC1, possibly in complex with other chromatin modifying enzymes, to E2F-regulated promoters. Expression of p107 (RBL1) is cell cycle regulated, with its levels peaking in late G1 and S phase. Although p107 (RBL1) is phosphorylated by cyclin D assocaited kinases during late G1 phase, a small pool of p107 (RBL1) is thought to be present throughout G1 and S phase, and could be involved in fine tuning the transcription of S-phase genes. This is supported by studies showing that unlike RB1 and p130 (RBL2), which are able to induce G1 arrest when over-expressed, p107 (RBL1) over-expression can arrest the cell cycle in both G1 and S phase. For recent reviews on the function of p107, p130 and pocket proteins in general, please refer to Wirt and Sage, 2010, MacPherson 2008 and Cobrinik 2005.

Summary from Reactome (R-HSA-1538133), read 2026-09-23.