Effect of (A) staurosporine and (B) the protein kinase A inhibitor H89 on eosinophil aggregation induced by PAF, C5a, or LTB₄ . Eosinophils were pretreated for 3 minutes with vehicle (▪), staurosporine (10⁻⁷ mol/L; □), or H89 (10⁻⁵ mol/L; □) before the addition of PAF (10⁻⁸ mol/L), C5a (10⁻⁷ mol/L), or LTB₄ (10⁻⁸ mol/L). Results are expressed as the percentage of maximal aggregation induced by PMA (10⁻⁷ mol/L) and each point is the mean ± SEM for four experiments. *P < .05 when compared with control values.