Enforced expression of MLL-AF4 in CD34⁺ HSPCs. (A) Schematic representation of the lentiviral vectors used. (B) Fluorescence (right) and phase-contrast (left) images of EV-transduced (top) and MLL-AF4-transduced (bottom) CD34⁺ HSPCs. On the right, images showing the percentage of GFP⁺ cells in EV-transduced (top) and in MLL-AF4-transduced (bottom) CD34⁺ HSPCs. (C) Representative genomic PCR and RT-PCR confirming proviral integration (gDNA) and expression of MLL-AF4 transcript (mRNA) in transduced CD34⁺ HSPCs (n = 3).