While TP53 mutations are common in UV-driven MCCs, they are rare in viral-driven MCC (10, 43, 45, 102) conceivably because sTAg upregulates MDM2 and the MDM4 activator CK1α to repress p53, thus abrogating the need for mutational inactivation (149). The gene discussed is TP53; the disease is Merkel cell skin cancer.