Levels of human engraftment of MLL-AF4–expressing CD34⁺ HSPCs into irradiated transplanted NSG mice. (A) Long-term hematopoietic reconstitution of NSG mice (n = 35) after IBMT of EV- or MLL-AF4–expressing CD34⁺ HSPCs. Engraftment was considered as percentage of hCD45⁺ more than 1% in the mouse BM. Each dot represents an individual mouse, and the horizontal line indicates the mean of each experimental cohort. The right panel represents the fold increase in the engraftment observed between both groups. (B) Levels of human chimerism in the distinct hematopoietic tissues analyzed. The consistent higher engraftment levels in animals transplanted with MLL-AF4–expressing CD34⁺ HSPCs, regardless of the tissue analyzed. (C) Representative genomic nested PCR and RT-PCR confirming proviral integration (gDNA) and stable long-term expression of MLL-AF4 transcript (mRNA) in mice killed 12 weeks on IBMT. (D) HoxA9 RT-PCR of CFUs from EV- and MLL-AF4–infected CD34⁺ HSPCs.