This application has as its fundamental premise the concept the concept that the therapy of the acute nonlymphocytic leukemias can be approached, the initiation of terminal differentiation and that this phenomenon can be induced by granulocyte-colony stimulating factor (G-CSF) to produce therapeutic benefit to patients with these diseases. This study will involve the role of the G-CSFR in the regulation of hematopoietic cell differentiation; evaluation of the synergistic interaction between RA and G-CSF on leukemia cell differentiation; extension of in vitro findings in the WEHI-3B leukemia in vitro to therapeutic evaluation in mice; and extension of findings in the WEHI- 3B leukemia to the clinical level.