Transgenic overexpression of VEGF-C does not affect the number or frequency of papillomas and squamous-cell carcinomas that form in mice. (A) Incidence of skin papilloma formation, over time (weeks), in VEGF-C transgenic mice (n = 31; ▪), compared with control mice (n = 32; ○). Incidence is expressed as the percentage of mice with detectable papillomas (> 1 mm) during the 20 weeks of topical PMA application. (B) No significant increase in the frequency (average number of papillomas per mouse) of papilloma formation was observed in VEGF-C transgenic mice. (C-D) No differences were observed in incidence or number of large papillomas more than 3 mm that formed in VEGF-C transgenic mice, compared with control mice, over the 20-week period of carcinogen application. (E-F) When mice were observed for an extended time period (33 weeks), squamous-cell carcinomas (SCCs) developed in both control and VEGF-C transgenic mice with the same incidence and numbers. (G) A comparable percentage of large papillomas underwent malignant conversion into SCCs in VEGF-C transgenic mice and control mice.