Increased expression of VEGFR-3 in tumor-associated lymphatic vessels of VEGFC transgenic mice. Immunofluorescence analysis of LYVE-1 (red) and VEGFR-3 (green) expression was performed in SCC samples from control (A,C,E) and VEGFC transgenic (TG; B,D,F) mice. Based on LYVE-1 expression, the SCCs of VEGFC transgenic mice demonstrated prominent lymphangiogenesis (B), whereas tumor-associated lymphatic vessels were less pronounced in SCCs of control mice (A). Expression of the VEGF-C receptor (VEGFR-3) was strongly up-regulated in the tumor-associated lymphatic vessels of VEGF-C–overexpressing mice (D). Merging of images revealed that VEGFR-3 expression completely colocalized with that of LYVE-1 (F, yellow to orange), whereas VEGFR-3 was only weakly expressed in the tumor-associated lymphatic vessels of control mice (C,E). (A-F) Scale bars represent 200 μm.