MLL-AF4 expression promotes progenitor clonogenic potential. (A) Primary and secondary CFU (10×) platings showing a higher overall CFU potential (*P < .05) in MLL-AF4- versus EV-transduced CD34⁺ cells (n = 4). The CFU types were not different between EV- and MLL-AF4–transduced CD34⁺ HSPCs. Error bars represent the SEM from 4 independent experiments. (Inset) Representative phase-contrast pictures of different CFU subtypes, including granulocyte, macrophage, granulocyte-macrophage, mix, and erythroid colonies. Pictures were captured (10×/0.25 PhP objective) with an inverter microscope Olympus CKX41. For analysis and image processing, a Color View Soft Images System software (Olympus V-TV1X-2) was employed. (B) Representative RT-PCR showing the presence of GFP and MLL-AF4 transcripts in CFUs plucked from EV- or MLL-AF4–transduced CD34⁺ CFU cultures. To ensure the availability of amplifiable template, cDNA from CFUs was subjected to Line-1 RT-PCR.