Phosphorylation of MAP kinases in response to stimulation with PF-4 and TNF. Neutrophils were stimulated with either PF-4 (4 μM) or TNF (9 ng/mL) alone or a combination of both stimuli for the times indicated. Activation of p38 and Erk MAP kinases was evaluated by Western blot analysis using antisera against the dual-phosphorylated (activated) MAP kinases. Blots were stripped and reprobed with p38 and Erk1/2 antisera to confirm equal protein loading. The data from one representative experiment of 5 are given.