““The fact that the genome also encodes genes to repair damage to the genome was discovered by several geneticists, including Evelyn Witkin and Steve Elledge. Witkin and Elledge, working independently, identified an entire cascade of proteins that sensed DNA damage, and activated a cellular response to repair or temporize the damage (if the damage was catastrophic, it would halt cell division). Mutations in these genes can lead to the accumulation of DNA damage-and thus, more mutations-ultimately leading to cancer. The fourth R of gene phyisiology, essential to both the survival and mutability of organisms, might be "repair.””
