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). The gene discussed is CSF3; the disease is acute myeloid leukemia.