This proposal will investigate the molecular mechanisms used by the abl oncogene in its normal and abnormal growth regulation. Comparison of the structures, regulation, hematopoietic transformation activities, and tyrosine kinase enzymatic properties of the murine cellular, and viral forms of the abl gene as well as the translocation derived form of the abl gene found in Chronic Myelogenous Leukemia cells will be performed. Emphasis will be placed on establishing transformed cell models for murine stem cell populations under the regulation of abl or other oncogenes in concert with improved culture techniques. These studies should aid our understanding of the mechanisms of oncogenesis and hematopoietic development.