EMPA inhibits high glucose (HG)-induced oxidative stress-dependent TRAF3IP2 expression in HK-2 cells. A, HG induces TRAF3IP2 expression in a biphasic manner. Quiescent HK-2 cells incubated with high glucose (25 mM) for the indicated time periods were analyzed for TRAF3IP2 expression by immunoblotting. Tubulin served as a loading control. B, C, HG induces TRAF3IP2 expression via oxidative stress. Quiescent HK-2 cells were incubated with Tiron, Tempol, DPI, gp91 ds-tat, EMPA (B) or GKT 137831 (5 mM in DMSO for 15 min; C) or prior to HG addition for 30 min. TRAF3IP2 expression was analyzed as in panel A. A-C, The intensity of immunoreactive bands from three independent experiments was semi quantified by densitometry and summarized in the accompanying bar graphs. * P < .05 versus Con; † P < at least 0.05 versus HG.