FIGURE 5.

ERK1/2 mediated ER Ca²⁺ release-induced eNOS Ser-635 phosphorylation. BAECs were pretreated with PD98059 or U0126 for 15 min and then subjected to TG stimulation. A, effect of ERK1/2 inhibition (PD98059, 20 μm) on ERK1/2 activation and eNOS Ser-635 phosphorylation in TG-treated cells. B, U0126 (10 μm), another MEK inhibitor that is structurally different from PD98059, also prevented ERK1/2 activation and eNOS Ser-635 phosphorylation in TG-stimulated cells. C, quantitative analyses of the effects of PD98059 and U0126 on ERK1/2 activation. The data are shown as the means ± S.E. (**, p < 0.01; n = 5). D, quantitative analyses of the effects of ERK1/2 inhibition on ER Ca²⁺ release-induced eNOS Ser-635 phosphorylation (*, p < 0.05; **, p < 0.01; n = 5). E, in vitro protein phosphorylation assays showing that active ERK2 directly phosphorylated eNOS Ser-635 residues. Representative blots are shown from three triplicate experiments.