P2RX7 agonist-induced p90Rsk phosphorylation in RAW 264.7 macrophages, which were pretreated for 15 min with vehicle (DMSO) or the MEK1/2 inhibitor UO126 at concentrations from 1 μM to 30 μM. The cells were subsequently treated with vehicle (2.5 mM HEPES), 250 μM BzATP, or 3 mM ATP for 15 min. A representative immunoblot displaying p90Rsk phosphorylation (pp90Rsk) is shown. Immunoblotting was performed with anti-β-tubulin antibody as a loading control. The results of three independent experiments were collated and are represented as a percent of nucleotide-induced p90Rsk phosphorylation (mean±sem); *, P < 0.05, as compared with DMSO-pretreated, BzATP-induced p90Rsk phosphorylation; Ψ, P < 0.05, as compared with DMSO-pretreated, ATP-induced p90Rsk phosphorylation.