Problem: One reason that cancer cells grow faster than normal cells is that they often ignore the checkpoints that normal cells pay attention to. Many cancer therapies exploit the loss of these checkpoints. For example, radiation therapy damages DNA indiscriminately, affecting both healthy and cancerous cells. In response to radiation damage, healthy cells arrest due to the G1/S checkpoint. This temporary arrest allows them to attempt to correct the DNA damage before DNA replication begins. However, cancer cells are less likely to pause to repair their DNA and, as a result, are more vulnerable to radiation therapy.