Nox4 is involved in insulin-stimulated insulin receptor and IRS tyrosine phosphorylation, ERK1/2, and AKT activation.

<p>HMVECs were treated with Nox4 siRNA or scrambled control siRNA for 24 hours, and then incubated with serum-free medium for 16 hours. (A) The tyrosine phosphorylated and total insulin receptor, (B) The tyrosine phosphorylated, the serine phosphorylated, and total IRS-1 protein levels were measured after stimulation with 100 nM insulin for 5 minutes. (C) Phosphorylated and total ERK1/2, (D) phosphorylated and total AKT, and (E) SHIP-1, MKP-1, Nox4, and β-actin protein expressions were determined after stimulation with 100 nM insulin for 30 minutes. Densitometry values (bottom) were normalized as the indicated. *<i>P</i><0.05, **<i>P</i><0.01 vs. the control siRNA group; #<i>P</i><0.05, ##<i>P</i><0.01 vs. the insulin+control siRNA group.