MLL-AF9 translocated cells preferentially express CD9. (A) Representative flow cytometry analyses are shown for cell-surface protein expression of genome-edited MLLr cells compared with control cells (CD34⁺ cells nucleofected with GFP alone) at day 65. (B) Representative flow cytometry plots of CD9 expression over time in culture for genome-edited MLLr cells. (C) Representative flow cytometry plots before and after FACS sorting of genome-edited MLLr cells based on CD9 expression at day 37 of in vitro culture followed by FISH analysis for MLL translocation. (D) Representative flow cytometry plots of CD9 expression on MLLr leukemic patient samples. Red shading indicates control (fluorescence minus one); blue line denotes expression of indicated marker. SSC, side scatter.