CSF2 and acute myeloid leukemia: Several studies have indeed demonstrated that the in vitro sensitivity to cytarabine of AML cells could be enhanced by preincubation with granulocyte colony-stimulating factor (G-CSF) and/or with granulocyte–macrophage colony-stimulating factor (GM-CSF) (Butturini et al, 1990; Bai et al, 1999).