Involvement of NADPH oxidase and mitochondria in cytosolic cytochrome c release and apoptosis. ARVMs were pretreated with NAC, APO, MnTBAP, or GLIB for 30 min followed by treatment with OPN for 6 h (a) or 24 h (b). a Cytosolic fractions were analyzed by Western blots using anti-cytochrome c antibodies. The lower panel exhibits the mean data normalized to GAPDH, *p < 0.05 versus CTL; $p < 0.05 versus OPN; n = 3–7. b Apoptosis was measured using TUNEL-staining assay, *p < 0.05 versus CTL; $p < 0.05 versus OPN; n = 6–8