RB1 and cancer: Furthermore, it has been shown recently that both noncancer and cancer cells bifurcate into two subpopulations after anaphase, marked by increasing vs. low CDK2 activity and the hyper- vs. hypophosphorylation of RB, delineating one subpopulation that never “uncrosses” the restriction point and continues cycling and another subpopulation that exits mitosis into an uncommitted pre-restriction point state [15].