Cell fate determination during G1 phase progression.

During the cell cycle, a cell may encounter one of five different fates: it can proliferate, differentiate, become quiescent or senescent, or go into apoptosis. The initiation of such fates is often seen in the G1 phase. The aim of this review is to describe an integrative model of G1 phase progression and cell fate determination. Along the G1 phase, the cell will encounter an early checkpoint after which apoptosis can result. For a quiescent state and for differentiation, the cell will exit G1 before the restriction point and a subsequent differentiation checkpoint will decide the fate of the cell, quiescence or differentiation. After the restriction point, the cell can be arrested in response to stress stimuli, such as telomere depletion, and a decision between senescence and apoptosis occurs.