Effect of PD98059 on the phosphorylation of p42^ERK2.

Purified neutrophils were incubated with either DMSO or 30 μM PD98059 for 30 minutes before stimulation with either (A) 1 μM FMLP, (B) 500 U/mL TNF-α, or (C) 10 ng/mL GM-CSF or FCS diluent for the times indicated. Phosphorylation of p42^ERK2 was measured by gel retardation as described in “Materials and methods.” The data shown are from a single experiment that was performed twice with similar results.