Increased tumor metastasis to sentinel lymph nodes in VEGFC transgenic mice. (A-D) Flow cytometry was used to calculate the percentage of GFP-expressing tumor cells in primary squamous-cell carcinomas (SCC; A-B) and in sentinel lymph nodes (LN; C-D) of control and VEGFC transgenic mice. Of all SCC-associated cells, 25.5% in the control GFP-transgenic mice and 23.8% in the VEGFC transgenic mice were observed to be GFP positive (A-B). Eight weeks after the first cutaneous SCCs were detected, the number and percentage of GFP-expressing tumor cells was significantly higher in metastases that formed in the sentinel lymph nodes of the VEGFC transgenic mice (44.5%) than of the control GFP-transgenic mice (0.3%; C). Data are expressed as mean ± SEM (n = 5 per group). (E) Fluorescence microscopy analysis revealed an increased incidence of sentinel lymph node metastasis in VEGFC transgenic mice, compared with control mice (n = 12). (B,D,E) ***P < .001; *P < .05; NS = no significance.