Catalytic activity is required for UCH-L1 induced tumorigenesis. (A) Schematic of the DMBA carcinogen bioassay. A single dose of DMBA was applied to the skin of mice between 1 and 3 days of life, and mice were analyzed at age 5 months for tumors. (B) The incidence of skin tumors for mice from panel A is shown. (C-D) Lymphoma-free survival is shown for mice with the indicated genotypes. P values were calculated with log-rank test. NS, not significant (P < .05).