Answer: Tumor suppressor genes.
Cell cycle is a sequence of events taking place inside the cell for its duplication.Tumor suppressor gene as the name suggests,it helps in the suppression of tumor or protecting the cell from getting cancerous.
This is done by inhibiting transition of stage of the cell cycle.In such condition the cell is either allowed to repair or undergo apoptosis if repair is not possible.
An example of tumor suppressor gene is : p53