CD34 and acquired polycythemia vera: Then, to evaluate the effects of mTOR inhibitors on the colony-forming activity of hematopoietic progenitors from MPN patients, bone marrow mononuclear cells or CD34+ cells from PMF and PV patients and healthy controls were cultured in the presence of cytokines optimally supporting the growth of BFU-E, CFU-G/GM or CFU-Mk.