GSTpi inhibits the destabilization of membrane VE-cadherin in human pulmonary microvascular endothelial cells (HPMECs). HPMECs were transfected with pcDNA3.1, Flag-GSTpi or Flag-GSTpi(Y7F) and further treated with TNF-α (50 ng/mL). (A–B) Endothelial cell permeability and TEER were measured and calculated (TNF-α (50 ng/mL) for 1 h). VE-cadherin internalization was measured by (C) immunofluorescence (scale bar = 25 μm, the yellow arrowheads indicate the internalization of VE-cadherin) and (D) analysis of cell membrane and cytoplasmic VE-cadherin protein levels (TNF-α (50 ng/mL) for 30 min). (E) Level of phospho-VE-cadherin, phospho-p120, phospho-β-catenin and phospho-Src (Tyr416) were measured and calculated (TNF-α (50 ng/mL) for 30 min). (F) Co-immunoprecipitation of Src and GSH was performed, and relative Src glutathionylation levels were measured and calculated (Up panel: IP results come from different blots with same samples; low panel: IP results come from same blot. TNF-α (50 ng/mL) for 30 min). *, compared with the pcDNA3.1 group; #, compared with the pcDNA3.1 + TNF-α group. Data are expressed as means ± SDs (n = 3). Data were analyzed by unpaired Student's t-tests. * or #, P < 0.05; ** or ##, P < 0.01. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)