Increased tumor lymphangiogenesis and angiogenesis in VEGF-C transgenic mice. Immunofluorescence analyses of CD31 (green) and LYVE-1 (red) expression in normal skin (A-B), early papillomas (C-D), and SCCs (E-F) of control (WT; A,C,E) and VEGF-C transgenic (VEGFC TG; B,D,F) mice revealed increased vascularization of papillomas and SCCs in VEGF-C transgenic mice and in control mice, compared with their PMA-treated skin. Tumor lymphangiogenesis was more prominent in VEGFC transgenic mice (D,F) than in control mice (C,E), with increased numbers of enlarged lymphatic vessels (red). Slight increases in the amount of tumor angiogenesis (green) in SCCs of VEGFC transgenic mice (F) were also observed, compared with that of control mice (E). Nuclei are labeled blue (Hoechst stain). (A-F) Scale bars represent 200 μm. (G-H) Computer-assisted morphometric analysis of normal cutaneous vessels and of tumor-associated lymphatic and blood vessels was performed. A significant increase in the relative area occupied by blood vessels in the peritumoral area of SCCs (Peri SCC), as well as within SCCs (Intra SCC), was observed in VEGFC transgenic mice (TG; ▪), compared with that of the control mice (WT, □) (G). A significant increase of the relative area occupied by lymphatic vessels was observed in the VEGFC transgenic mice, throughout all stages of skin carcinogenesis (H). Skin indicates PMA-treated normal skin (n = 7); SP, small papillomas (1-3 mm; n = 6); LP, large papillomas (> 3 mm; n = 6); and SCC, squamous-cell carcinoma (n = 7). Data are expressed as mean ± SEM. *P < .05; **P < .01; ***P < .001; NS = not significant.