Abstract
The continuum model of the mammalian division cycle proposes that there are no Gl-phase specific controls or events. The G1 phase is simply the time when processes begun in the previous cell cycle are completed. In this review, the continuum model is applied the variability of the Gl-phase, the existence of Gl-less cells, the ubiquitous Gl-phase arrest phenomenon, the effect of over-expressed cyclins on Gl-phase length, the statistical variation of the cell cycle, the reports of Gl-phase syntheses, the proposed variation in retinoblastoma protein phosphorylation in Gl-phase, and the myriad findings put forward to support the Gl-control model of the mammalian division cycle. The continuum model is a valid description of the mammalian division cycle.