Intracellular and extracellular VEGFR2 protein concentrations in HEK293 cells under different transfection conditions. ELISA was used to detect the intracellular and extracellular VEGFR2 protein concentrations in HEK293 cells. Liposomes and DNA were added at a 1:1 (w/w) ratio to HEK293 (seeding density 4 × 104 cells/well). Truncated-Vegfr2 indicates transfection with 0.15 μg of pCMV6-truncated Vegfr2 plasmid plus 0.10 μg pCMV-gfp plasmid/well. Rat-Vegfr2 indicates transfection with 0.15 μg of pCMV6-rVegfr2 plasmid plus 0.10 μg pCMV-gfp/well. Control indicates transfection of 0.10 μg/well pCMV-gfp alone. rVegfr2: rat-Vegf-receptor2. *: P < 0.05.