Fig. 2. Effect of shear stress on the activation of Src and phosphorylation of PECAM-1. (A) Endothelial cells were maintained under static conditions or exposed to fluid shear stress (12 dynes cm^–2, 5-60 minutes) and the phosphorylation of Src on Tyr⁴¹⁶ as well as total Src levels were detected using specific antibodies. The bar graph summarizes data obtained in four independent experiments; ^*P<0.05, ^**P<0.01 versus static conditions. (B) Endothelial cells were exposed to fluid shear stress (12 dynes cm^–2, 30 minutes) in the absence (CTL) and presence of the Src kinase inhibitor PP1 (30 µmol l^–1). Thereafter, PECAM-1 was immunoprecipitated and the tyrosine phosphorylation of PECAM-1 was assessed by western blotting. The results shown represent data obtained in three independent experiments.