L-DM1-methyl disrupts microtubule organization in mouse culture megakaryocyte and mouse/human platelets. The effect of 2, 20, and 200 ng/mL of L-DM1-methyl on cultured mouse megakaryocytes and mouse/human washed platelets was examined. Samples were probed for β1-tubulin to delineate their microtubule cytoskeleton. Cultured mouse megakaryocytes (A) and mouse/human platelets (B-C) demonstrated reduced proplatelet elongation and microtubule disruption characteristic of T-DM1 treatment.