Representative confocal images of dihydroethidine staining (red fluorescence) in endothelial cells of en face aortas from C57Bl/6 (A), TGFβ1 (B), apoE−/− (C), and apoE−/− × TGFβ1 mice (D). Original magnification, ×1,000. Hoechst counterstaining of endothelial cell nuclei is shown as pseudocolor green. Nuclei of cells that exhibit significant superoxide production appear in yellow (red + green). Bar graph (E) shows summary data for fluorescence intensity of dihydroethidine staining (fold change values compared with control C57Bl/6). Data are means ± SE. *P < 0.05.