For example, in murine retroviral models, Lmo2 and Hhex were mutually exclusive integrations (14); and, we previously showed occupancy of LMO2 and its partner, LDB1 at the intron one enhancer of HHEX in multiple human leukemic cell lines but it was not clear whether this enhancer was sufficient to activate HHEX in ETP-ALL. The gene discussed is LDB1; the disease is acute lymphoblastic leukemia.