Figure 2. Knockdown of endogenous PTP1B by siRNA enhances VEGFR2 autophosphorylation.
HUVECs were transfected with scrambled or PTP1B siRNA. A, PTP1B activity (upper graph) and PTP1B protein expression (lower blot). PTP1B activity was expressed as fold change from control (the ratio in untransfected cells was set to 1). * P<0.05 vs. Scrambled siRNA. B, Cells were stimulated with VEGF (20 ng/ml) and lysates were immunoprecipitated with anti-VEGFR2 antibody, followed by immunoblotting with anti-pTyr or VEGFR2 antibody. Bottom panel shows averaged data, expressed as fold change of phosphorylation over basal (means ± S.E., n=3). *P<0.05 vs. Scrambled siRNA at each time point.