Temporal events regulating the early phases of the mammalian cell cycle

It is proposed that the regulation of the pathways directing mammalian cell cycle progression involves several oncogenes. A summary of what is known about some of these regulatory oncogenes (fos, jun, myc, and Rb-1) and where they might function in the progression of a cell from G0 to G1 and G1 to S is presented. Data on two replication-dependent genes, those encoding histones and thymidine kinase, respectively, are also presented as models for describing transcriptional and post-transcriptional events at the G1-S border.