Relative to wild-type mice, p53-null mice developed fewer tumors, averaging 4.05 fewer papillomas (95% CI (−6.10, −2.00); p = 0.0001) 10–16 wk after the DMBA administration, while p19 Arf-null mice averaged 2.68 more papillomas (95% CI (0.52, 4.84); p = 0.015) 18–40 wk after the DMBA administration (Figure 5A). This evidence concerns the gene TP53 and papilloma.