VEGFR-2 is required for RhoC signaling, but VEGFR-2 phosphorylation is negatively regulated by RhoC. HUVECs were transfected with control or VEGFR-2 siRNA, serum-starved overnight, and treated with 10 ng/ml VEGF-A for 2, 5, 10 or 15 min (+V2, +V5, +V10 and +V15, respectively). (A) Lysates were immunoprecipitated with GST beads and GTP-bound RhoC was detected by immunoblotting (IB). Levels of total RhoC, RhoA, VEGFR-2 and β-actin (loading control) are shown. (B) Lysates were immunoblotted for phosphorylated VEGFR-2 (pVEGR-2) Y1175, pVEGFR-2 Y951, pVEGFR-2 Y1059, total VEGFR-2 and β-actin (loading control). (C) Lysates were immunoprecipitated (IP) with anti-phosphorylated-tyrosine (pTyr) antibody and immunoblotted with antibody against VEGFR-2. Vertical lines indicate where lanes were removed and composite images were generated from the same immunoblot. Experiments were repeated at least three times.