Transgenic VEGF-C expression is maintained during skin carcinogenesis. In situ hybridization demonstrates strong expression of human VEGFC mRNA in squamous-cell carcinomas (SCCs) of VEGF-C transgenic mice. (A) In primary tumors, SCC cells express high levels of VEGFC mRNA, as indicated by hybridization to an antisense human VEGFC probe. (B) In SCC metastases that form in sentinel lymph nodes (LNs), this expression of VEGF-C mRNA is maintained. (C-D) A human VEGF-C sense control probe did not hybridize with tumor samples. (A-D) Scale bars represent 100 μm. (E) ELISA analysis of human VEGF-C protein expression in skin and tumor lysates (n = 5 per group) revealed significant increases in the levels of VEGF-C protein in SCCs that form in VEGF-C transgenic mice, compared with the normal skin of these mice. No human VEGF was detected in skin or tumor lysates of control mice. Data are expressed as mean ± SD; ***P < .001.