Figure 1.

Development of skin lesions in mice treated with DMBA + TPA. (a) The average number of papillomas (top panels) or macroscopic nevi/melanomas (lower panels) per mouse was scored, grouped by size (diameter of the lesions in mm), and represented for each genotype: Cdk4^+/+ (n =13), Cdk4^+/R24C (n =13), and Cdk4^R24C/R24C (n =20). Because a significant fraction of Cdk4^R24C/R24C mice are dead by week 21, the statistical representation of their skin lesions was stopped at week 20. (b) Representative pictures taken at week 20. White arrows indicate papillomas, and black arrows show the position of small nevi (Cdk4^+/+) or melanomas (Cdk4^+/R24C and Cdk4^R24C/R24C).