Cell cycle, illustration. The cell cycle, or cell-division cycle, is the cycle of events that occurs in a cell resulting in its division into two daughter cells. In the G1 phase (Gap 1) the cell grows. It may leave the cell cycle during this phase and become quiescent (G0, resting phase). This phase can last indefinitely, or the cell can return to the cell cycle. During the S phase (synthesis) DNA replication occurs. In the G2 phase (Gap 2) the cell continues to grow, before entering the M phase (mitosis) where it divides into two daughter cells which continue the cycle. The whole cycle is divided into two main stages: interphase, incorporating G1, S and G2, and the mitotic (M) phase.