Dasatinib inhibits neutrophil functions triggered by immobilized immune complexes. Human neutrophils pretreated with the indicated concentrations of dasatinib were plated on a surface coated with immobilized IgG immune complexes (IC), followed by microscopic observation (A) and quantification (B) of cell spreading, measurement of respiratory burst (C), assessment of lactoferrin (D) and gelatinase (E) release, analysis of phosphorylation of total cellular proteins and the phosphorylation of the p38 MAPK and Syk (Tyr352) by immunoblotting (F), or analysis of Syk phosphorylation by immunoprecipitation (IP), followed by immunoblotting for phosphotyrosine (PY) residues (G). Panels A, E, and F show representative data from 3-4 independent experiments. The kinetic/bar graphs in panels B through D show mean and SD of representative experiments, and the dose-response curves in these panels show mean and SEM of the percent response from 3-4 independent experiments.