NOX2 regulates LSS production of NO via eNOS phosphorylation. siRNA against NOX2 was used to examine whether NOX2 plays a role in LSS activation of eNOS. A, Western blotting data of total and phosphorylated eNOS in bovine aortic endothelial cells treated with NOX2 siRNA and LSS (n = 4; *, p < 0.001; #, p < 0.001 versus all others). Of note, NOX2 siRNA inhibited LSS activation of eNOS. B, superoxide production in cells treated with NOX2 siRNA and LSS (n = 4; *, p < 0.001 versus static; #, p < 0.05 versus static control siRNA; &, p < 0.05 versus LSS control siRNA). C, NO production in cells treated with NOX2 siRNA and LSS (n = 4; #, p < 0.01 versus all others). Consistent with eNOS activation data, NOX2 siRNA attenuated NO production in response to LSS.