Syk and Ras are located upstream of Rac2 and JNK. Neutrophils were pretreated for 20 minutes with Src-kinase inhibitor PP1 (50 μM), Ras farnesyltransferase inhibitor manumycin A (15 μM), or Syk inhibitor piceatannol (40 μM) or without inhibitor and subsequently were stimulated with 4 μM PF4 for 5 or 20 minutes. Cells were lysed, and activation of Rac2 (A) or JNK (B) was determined as described in Figures 3 and 5B, respectively. Quantification of relative density of protein bands was performed using Odyssey software 1.2 (background method: median, top/bottom). Band density in untreated cells was set as 100%, and the densities of protein bands in inhibitor-treated cells were calculated as percentage of untreated cells. Data represent mean ± SD of 5 independent experiments. Statistical analysis using one-way ANOVA indicates significant differences (^*P < .045) between inhibitor-treated and untreated samples based on the data from 5 individual experiments.