tokens: The effect of cycloheximide on granulocyte/macrophage progenitors ( CFU-GM ) after in vitro Ara-C exposure was examined using normal human bone marrow , malignant progenitors from patients with chronic myelogenous leukemia ( CML ) , and clonogenic cells from the human acute nonlymphocytic leukemia cell lines HL-60 and KG-1 .