Cell cycle and its control. G₀ stands for gap 0, G₁ for gap 1, S for synthesis, G₂ for gap 2, and M for mitosis. Cell cycle includes interface (G₁, S, and G₂), and M (including prophase, metaphase, anaphase, and telophase). Nondividing cells (G₀ or resting phase) are not considered to be in the cell cycle. Cytokinesis follows mitosis. Checkpoint G₁/S decides if cells go to rest (G₀) or to S. Checkpoint G₂/M decides if cells can begin mitosis. Checkpoint M occurs in metaphase of mitosis and it is in charge of biorientation.