Expression of NUP98/HHEX in murine bone marrow progenitors results in enhanced self-renewal and immortalization in vitro. (A) Representative (of 5 independent experiments) assay showing increasing number of colonies with successive replating for cells retrovirally expressing NUP98/HHEX or NUP98/HOXA9 and a rapid decline in bone marrow transduced with the empty pMSCV-IRES-EGFP vector. (B) NUP98/HHEX expression results in expansion of transduced (EYFP⁺) cells in IL-3–, IL-6–, and mSCF-containing medium. The insert confirms mRNA expression of the fusion as assessed by RT-PCR using primers covering the breakpoints. Error bars represent SD from 3 independent experiments. (C) Immunophenotype of bone marrow cells from liquid cultures. Representative Wright-Giemsa–stained cytospin preparation of NUP98/HHEX- or NUP98/HOXA9-transduced bone marrow, cultured for 3 weeks in the presence of IL-3.