From this understanding, scientists then identified the four characteristic phases of the cell cycle: mitosis (M), gap 1 (G1), DNA synthesis (S), and gap 2 (G2). The study of these phases ...

Checkpoints are depicted as thick red bars. The stages of the cell cycle (G1: Gap 1, S: DNA synthesis, G2: Gap 2, and M: mitosis) are indicated. Tumor suppressors act to maintain checkpoints ...