CSF2 and acute myeloid leukemia: Primary AML cells derived from 68 unselected patients (Table 1) were cultured in suspension (six-well culture plates); the culture medium was only supplemented with thrombopoietin (TPO), Flt3 ligand (Flt3L), stem cell factor (SCF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin 3 (IL-3).