The Synthesis phase occurs in between two Gap phases (Gap 1 and Gap 2). By the end of Gap 1 phase, the cell will decide if it will proceed to the Synthesis phase (S phase) or if it will enter a period of dormancy called Gap 0 phase. The transition of the cell from Gap 1 to S phase is determined by certain factors, e.g. levels of nutrients, growth factors and energy.
- S phase