The chemokine stromal-derived factor-1 (SDF-1) is a chemoattractant for CD34⁺ progenitor cells, in vitro and in vivo. The receptor for SDF-1, CXCR-4, is a 7 transmembrane domain receptor, which is also a coreceptor for human immunodeficiency virus (HIV). Here we show that transformation of hematopoietic cell lines by BCR/ABL significantly impairs their response to SDF-1. Three different hematopoietic cell lines, Ba/F3, 32Dcl3, and Mo7e, were found to express CXCR-4 and to respond to SDF-1 with increased migration in a transwell assay. In contrast, after transformation by the BCR/ABL oncogene, the chemotactic response to SDF-1 was reduced in all 3 lines. This effect was directly due to BCR/ABL, because Ba/F3 cells, in which the expression of BCR/ABL could be regulated by a tetracycline-inducible promoter, also had reduced chemotaxis to SDF-1 when BCR/ABL was induced. The reduced response to SDF-1 was not due to an inability of BCR/ABL-transformed cell lines to migrate in general, as spontaneous motility of BCR/ABL-transformed cells was increased. In mice, injection of SDF-1 into the spleen resulted in a transient accumulation of untransformed Ba/F3 cells, but not Ba/F3.p210^BCR/ABL cells administered simultaneously. The mechanism may involve inhibition of CXCR-4 receptor function, because in BCR/ABL-transformed cells, CXCR-4 receptors were expressed on the cell surface, but SDF-1 calcium flux was inhibited. Because SDF-1 and CXCR-4 are felt to be involved in progenitor cell homing to marrow, the abnormality decribed here could contribute to the homing and retention defects typical of immature myeloid cells in chronic myelogenous leukemia.