Serum-free culture of sorted VEGFR2⁺ cells expressing VEGFR3 and its kinase-negative mutants. (A) VEGFR2⁺ cells transfected with mock, VEGFR3(WT), and its kinase-negative mutant cDNAs were cultured in SFO3 serum-free medium with VEGF-A (40 ng/mL), VEGF-C (400 ng/mL), or VEGF-A and VEGF-C. After 2 days, cells were doubly stained with anti–PECAM-1 (purple) and anti-SMA (brown) antibodies. (B) Differentiated cells were observed by phasecontrast microscopy. Scale bar, 100 μm.