Sunburn (UV) causes keratoses in about 60% of the cases. The p53 gene may suffer mutation(s), mainly C→T transitions. These p53 mutant cells, after clonal propagation, may develop into squamous cell skin cancer (SCC). In over 90% of the SCC cells, the p53 gene is mutant. The increased melanin production involved with ultraviolet light exposure may be correlated with the DNA repair system.  P53,  keratoses,  DNA repair,  ultraviolet light,  pigmentation in animals,  melanoma