This grant will address several aspects of the potential affects of bioactive agents on leukemia cells in vivo. Leukemia cells will be obtained before and after administration of these agents and the effects of these agents on the distribution of cell cycle times amongst the leukemia cells within individual patients will be explored. The effects of these agents on the expression of the protooncogenes fms, myb, IL1beta and myc will be studied as well. Initially, we will study the effects of retinoic acid/interferon and rhGM-CSF. The studies will be extended to other agents once these initial studies are completed. Parallel evaluation of the bioactive agents in vitro will be conducted so that predictive in vitro assays can be developed.