Proteins that are able to fulfil this role would satisfy the following six conditions: 1) regulation of the G1/S transition 2) regulation of cyclin D, cyclin E, or the CDK inhibitors 3) presence and activity in the mother G2, mother mitosis, daughter G0, or daughter G1 4) regulation by mitogens 5) regulation by DNA damage (opposite to the regulation by mitogens) 6) deregulation in cancer. The gene discussed is CCNE1; the disease is cancer.