Actin inhibitors, but not tubulin/Eg5 inhibitors, block enucleation of human erythroblasts. Mature erythroblasts were cultured in the presence of EPO with or without various concentrations of inhibitors for actin polymerization (cytochalasin D and NSC23766), tubulin (colchicine) and Eg5 (monastrol). (A) Effects of inhibitors and vehicle on the enucleation of mature erythroblasts. Results are presented as the mean ± SD of 3 independent experiments. (B) May-Grünwald-Giemsa staining of cells cultured for 24, 48 and 72 hours with or without 10 μg/mL cytochalasin D, 200μM NSC23766, 10 μg/mL colchicine and 100μM monastrol. A representative result of 3 independent experiments is shown. Scale bar = 10 μm.