Effect of different kinase inhibitors on PF-4–induced neutrophil adhesion to endothelial cells. Neutrophils were pretreated for 20 minutes with wortmannin (Wm; 20 nM), SB203580 (10μM), PD098059 (10 μM), PP1 (25 and 50 μM), SU6656 (25 μM) or without inhibitor and subsequently incubated with 2 μM PF-4 in the presence of a monolayer of cultured endothelial cells. After 20 minutes nonadherent cells were removed from endothelial cells layers and residual neutrophils were determined. The amount of cells in samples receiving PF-4 in the absence of any inhibitor was set at 100% and data were calculated as the percentage of these controls. Data represent mean ± SD of 4 independent experiments, each performed in duplicate. Asterisk (*) indicates significant differences (P < .0005) between inhibitor-treated and untreated samples based on the data from 4 individual experiments.