Internal monitors called checkpoints track each step of the cell cycle. In the cell cycle, there are three main checkpoints; one at the end of G1, a second at the transition of G2/M, and a third during the metaphase. Positive molecules of the regulator allow the cell cycle to proceed to the next level.
Mitosis, although continuous process, is conventionally divided into five stages: prophase, prophase, metaphase, anaphase and telophase.
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