NOX4 did not drive myofibroblast differentiation of human primary fibroblasts. A and B. NOX4 mRNA expression after treatment with DPI 1 μM and GKT137831 40 μM (A) and siRNA silencing of NOX4 gene ± compounds (B) in HFF cultured without or with TGF-β1; C and D. ACTA2 mRNA expression after treatment with DPI 1 μM and GKT137831 40 μM (C) and siRNA silencing of NOX4 gene ± compounds (D) in HFF cultured without or with TGF-β1; E and F NOX4 mRNA expression in hDFs (E) and p22phox mutated hDFs (F) cultured without or with TGF-β1 and DPI; G. and H. ACTA2 mRNA expression in hDFs (G) and p22phox mutated hDFs (H) cultured without or with TGF-β1 and DPI; HFF, n = 3; hDFs, n = 3; p22phox mutated hDFs, n = 3 or 4. Data shown as mean ± SD; ns – not significant, **p < 0.01, **p < 0.01, ***p < 0.001, ****p < 0.0001; One-way ANOVA.