Knockdown of β-catenin mimics the defective reannealing phenotype of endothelial junctions seen in FoxM1-deficient monolayers after PAR-1 activation. (A and B) siRNA dose response of knockdown of β-catenin. At 48 h after transfection with β-catenin scRNA, or siRNA at indicated doses, the confluent HMVEC-L were lysed for Western blot analysis of β-catenin protein levels. The same membrane was blotted with anti-actin for loading control (A). The experiment was performed three times with similar results. Densitometry was used to quantify the protein levels of β-catenin under each condition (B). Data are expressed as mean ± SD (error bars; n = 3 independent experiments). *, P < 0.05 versus scRNA. 1.5 µmol/L of β-catenin siRNA induces ∼50% knockdown of β-catenin protein level. (C) TER assay demonstrating that partial knockdown of β-catenin results in impaired recovery of endothelial AJ function after thrombin challenge. HMVEC-L transfected with either human β-catenin siRNA (siRNA, 1.5 µmol/L) or scRNA were plated on electrodes at confluency. At 48 h after transfection, TER of each monolayer at baseline was recorded and monitored for 6 h after the thrombin challenge (4 U/ml). The TER value of each monolayer was normalized to its value at baseline. Data are expressed as mean ± SD (error bars; n = 3 independent experiments). *, P < 0.05 versus scRNA.