Chrysin downregulated NOX4 expression induced by hypoxia in cultured PASMCs. (A) The expression of NOX4 mRNA was determined by real-time PCR. (B) The expression of NOX4 protein was determined by western blotting. Data are means ± SD from three independent experiments. Statistical analysis was performed with one-way ANOVA followed by the Newman–Student–Keuls test for multiple comparisons. NOX4: NADPH oxidase 4; DPI: diphenyleneiodonium chloride.