Microparticle production by megakaryocytes is a microtubule-independent process that is regulated by actin. Mouse megakaryocytes were cultured in the presence of vehicle alone (control), 0.001% DMSO, 1 μM nocodazole, 5 μM nocodazole, 1 μM latrunculin A, or 5 μM latrunculin A. Following an overnight incubation, supernatants were analyzed for CD41⁺ microparticles by flow cytometry. Values are reported as percentage of control compared with the number of microparticles detected in supernatants of megakaryocytes exposed to buffer alone. Error bars indicate the standard deviation of 4 independent assays.