Editing G2 phase (section)

=== Cyclin B1 synthesis and degradation ===
Cyclin B1 levels are suppressed throughout G1 and S phases by the [[anaphase-promoting complex]] (APC), an E3 ubiquitin ligase which targets cyclin B1 for proteolysis. Transcription begins at the end of S phase after DNA replication, in response to phosphorylation of transcription factors such as [[NFYA|NF-Y]], [[FOXM1|FoxM1]] and [[MYB (gene)|B-Myb]] by upstream G1 and G1/S cyclin-CDK complexes.<ref>{{cite journal | vauthors = Katula KS, Wright KL, Paul H, Surman DR, Nuckolls FJ, Smith JW, Ting JP, Yates J, Cogswell JP | display-authors = 6 | title = Cyclin-dependent kinase activation and S-phase induction of the cyclin B1 gene are linked through the CCAAT elements | journal = Cell Growth & Differentiation | volume = 8 | issue = 7 | pages = 811–20 | date = July 1997 | pmid = 9218875 }}</ref>