quality:correction, structural:summarization
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 NF-Y, FoxM1 and B-Myb by upstream G1 and G1/S cyclin-CDK complexes.