Stathmin 1 is an important cytoplasmic microtubule-destabilizing protein that plays critical roles in proliferation and accurate chromosome segregation through regulation of microtubule dynamics. High levels of Stathmin 1 expression have been reported in leukemia and solid tumors. However, Stathmin 1 has not been studied in myelodysplastic syndrome cells. We, herein, report that significantly higher Stathmin 1 levels were observed in proliferating hematopoietic cells, in high-risk MDS and acute leukemia cells. In addition, Stathmin 1 silencing in U937 and Namalwa leukemia cells reduced cell proliferation and clonogenicity. Our data suggest that Stathmin 1 expression may be related to the highly proliferative phenotype of hematopoietic cells and add new insights into the participation of Stathmin 1 in hematological malignancies.38251-7