In particular, leukemias with the t(11;19)(q23;p13.3) translocation express HRX-ENL fusion proteins and display features which suggest the malignant transformation of myeloid and/or lymphoid progenitor(s).     ///    Immortalized cells or enriched primary hematopoietic stem cells transduced with HRX-ENL induced myeloid leukemias in syngeneic and SCID recipients.     ///    "In contrast, wild-type ENL or a deletion mutant of HRX-ENL lacking the ENL component did not demonstrate in vitro transforming capabilities. "    ///    "To characterize directly the potential transforming effects of HRX-ENL on primitive hematopoietic precursors, the fusion cDNA was transduced by retroviral gene transfer into cell populations enriched in hematopoietic stem cells. "    ///    Immortalization and leukemic transformation of a myelomonocytic precursor by retrovirally transduced HRX-ENL..     ///    Immortalized cells contained structurally intact HRX-ENL proviral DNA and expressed a low-level of HRX-ENL mRNA. 