The involvement of Arp2/3 complex, which causes actin filament branching, in the effect of drugs glutoxim and molixan on intracellular Ca 2+ concentration was investigated. Using Fura 2AM microfluorim etry it was shown for the first time that Arp2/3 complex inhibitor CK 0944666 almost completely prevents the increase in intracellular Ca 2+ concentration, induced by glutoxim or molixan in macrophages. The data suggest the involvement of Arp2/3 complex in the glutoxim and molixan effect on the Ca 2+ signaling pro cesses in macrophages.