Figure 4. Knockdown of NOX4 by siRNA transfection inhibits vascular endothelial growth factor–induced reactive oxygen species generation in human retinal microvascular endothelial cells. (A) western blots of NOX4 expression and (B) reactive oxygen species (ROS) generation were determined with 434 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester (CMDCF-DA) fluorescence in human retinal microvascular endothelial cells (hRMVECs) transfected with control siRNA (ConsiRNA) or NOX4 siRNA (NOX4siRNA) and treated with PBS or vascular endothelial growth factor (VEGF; 20 ng/ml; ***p<0.001 versus PBS of ConsiRNA; ^†††p<0.001 versus standard deviation [SD], VEGF of ConsiRNA; one-way ANOVA with post-hoc Newman–Keuls multiple comparison testing).