NOX1 shRNA decreases radiation-induced fibrotic changes in HPAECs. (A) Cells transfected with NOX1-, 2- or 4-targeted shRNA were irradiated and incubated for 72 h, followed by western blot analysis of α-SMA, vimentin and CD31. Protein levels were quantified by densitometric analysis of the blots. Values are expressed as the mean ± standard deviation (n=3). **P<0.005; *P<0.05, α-SMA vs. Con (-). (B) HPAECs transfected with NOX1 shRNA were irradiated with 5 Gy and incubated for 72 h. Alexa 488-conjugated anti-FSP1 and Alexa 594-conjugated anti-VE-cadherin antibodies (green and red, respectively) were used to stain cells and nuclei were counterstained with 4′,6-diamidino-2-phenylindole (blue). HPAEC, human pulmonary artery endothelial cell; SMA, smooth-muscle actin; VE, vascular endothelial; NOX, nicotinamide adenine dinucleotide phosphate oxidase; CON, control; shRNA, small hairpin RNA; IR, irradiation; FSP fibroblast-specific protein.