TP53 and skin basal cell carcinoma: Interestingly, when we injected the virus into the tree shrew tail skins, the BCC tumor formed more easily than that on other parts of skin after only one dose containing 5μL of pCDH-SmoA1 virus (5.6×105 TU) and 5μL of lentiviral shRNA targeting p53 (2×105 TU).