PEDF decreases H/R-induced cytoplasmic ROS generation via PEDF-R. H9c2 cells were maintained in normoxic or H/R conditions for 8/2 h with or without PEDF (10 nM). RNA interference assays were used to silence PEDF-R. (A) XO activity was assessed in all experimental groups using the XO activity assay kit (n=4). (B) NOX activity was assessed in all experimental groups using the NOX activity assay kit (n=4). (C) Western blot analysis of rac1 protein expression, with (D) quantification (n=4). Data are expressed as the mean ± standard error of the mean. *P<0.05, with comparisons indicated by lines. PEDF, pigment epithelium-derived factor; H/R, hypoxia/reoxygenation; ROS, reactive oxygen species; PEDF-R, pigment epithelium-derived factor receptor; XO, xanthine oxidase; NOX, NADPH oxidase; rac1, RAC family small GTPase 1; si, small interfering.