Increased tyrosine phosphorylation in the stretched cell model. (A) Extracted BAEC models were stretched or unstretched for 10 min and double labeled with 4G10 and anti–pan-cadherin. Note that cells in the stretched monolayer are more clearly outlined by 4G10 staining than those in the unstretched sample. No significant changes were observed in anti-cadherin staining before and after stretching. Bipolar arrow indicates the direction of stretch. Bar, 20 μm. (B) BAECs cultured on an elastic substrate were treated with Lipofectamine only (LF control) or transiently transfected with PECAM-1 siRNA and then extracted. The extracted models were stretched or left unstretched for 5 min at 37°C and their tyrosine phosphorylated protein levels determined using 4G10 immunoblotting. Arrow indicates a 130-kD band whose phosphorylation level was diminished in PECAM-1 siRNA transfected cells.