FIG. 7.
Collaboration between pRb and Ras-oncogenic pathways in Cdk4R24C/R24C mice. (a) Kaplan-Meier survival curves of DMBA-TPA-treated Cdk4+/+ (n = 7) (+/+), Cdk4+/R24C (n = 13) (+/R24C), and Cdk4R24C/R24C (n = 28) (R24C/R24C) mice that were observed for 20 weeks for appearance of detectable or palpable tumors. Tumor-prone mice were euthanatized, and tumors were dissected and processed for histological analysis. (b to f) Treatment with DMBA plus TPA leads to the development of skin tumors (b) that are histologically characterized as papillomas (d to f). The histology of a normal tumor-free skin is shown (c). The normal epidermis (c) and the epidermal hyperplasia and papillomas (d to f) are indicated by arrows.