ICAM-1 activation of PKCα phosphorylation in HMVECLs is mediated by xanthine oxidase stimulation of ERK1/2.

<p>70% confluent monolayers of HMVECLs were pretreated with TNFα to induce ICAM-1 expression. <b>A</b>) Time course for anti-ICAM-1-coated bead stimulation of ERK1/2 Thr²⁰²/Tyr²⁰⁴ phosphorylation (P-ERK1/2). *, p<0.05 as compared to the nontreated control group. <b>B</b>) TNFα-pretreated HMVECLs were incubated for 1 hr with the pharmacological inhibitors allopurinol (0.3 mg/ml), U73122 (10 µM), and Go6976 (2.3 nM), apocynin (4 mM), or the solvent control DMSO (0.01%). The cells were nonstimulated (NS) or stimulated with anti-ICAM-1-coated beads and examined by western blot for ERK1/2 Thr²⁰²/Tyr²⁰⁴ phosphorylation and total ERK1/2. Shown are the means ± SEM from 3 experiments. Panel A: *, p<0.05 as compared to 0 minutes. Panel B: *, p<0.05 as compared to the anti-ICAM-1-stimulated group.