Effect of CP-532,903 on fMLP-induced Rac activation in mouse bone marrow neutrophils obtained from wild-type mice and from A3ARKO mice. Rac activity in whole-cell lysates was quantified using an ELISA-based assay kit (G-LISA kit, Cytoskeleton, Inc), as described under Materials and Methods. (A) The time-course of Rac activation following stimulation with fMLP (1 μM). (B & C) Rac activity 15 sec after the addition of 1 μM fMLP to wild-type (B) and A3KO (C) cells pretreated for 30 min with 100 nM CP-532,903 (CP). The data are presented as the percent increase over baseline activity. In control assays, cell lysates were incubated with 200 μM GTPγS. All assays were conducted in the presence of 1 unit/ml ADA. Mean ± SEM. *, p < 0.05 versus the fMLP-treated group by one-way ANOVA and Bonferroni’s t test, n = 3-7.