For skin squamous cell carcinomas (SCCs), the incidence of p53 mutations ranges from 50 to 90% in both humans and mice.17, 18 UVB-induced mutation of p53 allows keratinocytes upon successive UVB exposures to evade apoptosis19, 20, 21, 22 and cell cycle arrest.23 These defects have a critical role in skin cancer development. The gene discussed is TP53; the disease is skin squamous cell carcinoma.