BMI1 knockdown induces apoptosis in CD34⁺38⁻ cells. CB CD34⁺ cells were transduced with control (scrambled) scr-RNAi or BMI1-RNAi particles and sorted, and single cells were deposited in 96-well plates and cultured in stroma-free conditions (IMDM supplemented with 10% FCS, 10 ng/mL IL-3, and 100 ng/mL TPO). Wells were evaluated microscopically 1 day and 5 days after plating, and wells were classified as quiescence if 1 live cell was observed; if multiple cells were observed, they were classified as proliferation; and if no cells were seen, they were classified as apoptosis. A representative experiment of 3 independent experiments is shown, whereby individual 96 wells per group were analyzed.