Fig. 6. Vactosertib decreases transforming growth factor-β (TGF-β1)-induced production of hydroxyproline and extracellular matrix proteins. Fibroblasts were pretreated for 24 hours with Vactosertib (400 ng/mL) then exposed with TGF-β1 (10 ng/mL) for 48 hours. (A) Hydroxyproline assay. Each bar depicts the mean value (±standard errors) of four experiments per group. ^ap<0.05, compared with the control group; ^bp<0.05, compared with the TGF-β1 group. (B) Representative Western blot for plasminogen activator inhibitor-1 (PAI-1), collagen I, collagen III, collagen IV, and fibronectin expressions in fibroblasts. (C) Data are presented as the relative density of each protein normalized to β-actin. Each bar depicts the mean value (±standard errors) of four experiments per group. ^ap<0.05, compared with the control group; ^bp<0.05, compared with the TGF-β1 group. (D) Representative fluorescent immunocytochemistry of fibroblasts with antibodies against PAI-1, fibronectin, collagen I, and collagen IV. Nuclei were stained with DAPI (4,6-diamidino-2-phenylindole). Scale bar indicates 100 µm. The results were similar among four independent experiments.