Retroviral expression of BCR-ABL in murine bone marrow (BM) causes CML-like MPD with overproduction of maturing neutrophils [3], whereas the BCR-ABL kinase inhibitor imatinib induces hematologic and cytogenetic remissions in CML patients [4]. This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.