Transcriptional activity of the NUP98/HHEX fusion gene as shown by luciferase assays. (A) A luciferase reporter gene under the control of a promoter with 5 consecutive HHEX-binding sites was cotransfected into K562 cells with expression construct encoding NUP98/HHEX. (B) Coexpression of HHEX (1 μg) with increasing amounts of NUP98/HHEX (0.5-2 μg) reverted transcriptional repression mediated by HHEX into activation. Luciferase activity was corrected for transfection efficiency based on the activity of a cotransfected β-galactosidase construct. The transcriptional activating potential is expressed as the fold induction relative to the control. Bars represent the mean plus or minus SD of 3 independent experiments.