In the skin, p53 plays another role in fighting cancers. This is particularly dangerous, since the skin is constantly in a state of replacement from basal cells rising through the epidermis. Mutation is probably a relatively common occurance. The result is the peeling of skin that follows sunburn. Thus, peeling skin is a protective mechanism against skin cancer.
Sunlight causes skin cancers in two ways.
First, it mutagenizes the p53 gene. Second, the heterozygotes produced by the lack one of these gene have a selective advantage over those that have both normal genes. The wild-type cells are sloughed off after exposure to sunlight. These cells are then exposed to sunlight, and the second gene can be destroyed. Oncogenic viruses can function by having a protein that binds and inactivates p53.