A, time-dependent changes in the phosphorylation (p-) of AMPK, Akt, eNOS, and extracellular signal-regulated kinase (ERK) after adiponectin treatment (30 µg/ml). B, role of AMPK in the regulation of adiponectin-induced protein phosphorylation. HUVECs were transduced with an adenoviral vector expressing dominant-negative AMPK tagged with c-Myc (dn-AMPK) or an adenoviral vector expressing green fluorescence protein (Control) 24 h before serum-starvation. After 16-h serum starvation, cells were treated with adiponectin (30 µg/ml) for the indicated lengths of time. C, role of Akt in the regulation of adiponectin-induced protein phosphorylation. HUVECs were transduced with an adenoviral vector expressing dominant-negative Akt (dn-Akt) or an adenoviral vector expressing green fluorescence protein (Control) 24 h before serum starvation. After 16 h of serum starvation, cells were treated with adiponectin (30 µg/ml) for the indicated lengths of time. Representative blots are shown.