Cx43 and c-Src are responsible for high glucose-induced Tyr-phosphorylation of IκB-α. (A) GMCs were preincubated and maintained in 10 μM PP2 (c-Src inhibitor) or 10 μM PP3 (inactive analogue of PP2) for 30 min and until the end of the experiment. Cells were then incubated in normal glucose (NG; 5.5 mmol/L) or high glucose (HG; 30 mmol/L) for 30 min and IκB-α was immunoprecipitated with an anti-IκB-α antibody. Tyr-phosphorylation of IκB-α and total-IκB-α were then analyzed by immunoblotting. (B) GMCs were transfected with Cx43-siRNA or GFP-Cx43 under the condition of normal glucose (NG; 5.5 mmol/L). After 48 h of transfection, GMCs were exposed to high glucose (HG; 30 mmol/L) for 30 min. IκB-α was immunoprecipitated with an anti-IκB-α antibody, and Tyr-phosphorylation of IκB-α and c-Src, and total-IκB-α were analyzed by immunoblotting. Experiments were performed at least three times with similar results. *P<0.05 vs. normal glucose-treated group, #P<0.05 vs. 30 mmol/L glucose-treated group.