Transcriptional features of genome-edited MLL-AF9 translocated cells. (A) RT-PCR was performed on complementary DNA of genome-edited MLLr cells from 2 independent cultures to detect fusion transcripts. Closed arrowheads indicate MLL-AF9 and AF9-MLL fusion transcripts. Open arrowheads indicate the alternatively processed fusion transcripts, which lack MLL exon 11 and MLL exon 12 from MLL-AF9 and AF9-MLL, respectively. (B) Representative western blot analysis of MLL proteins in controls (nucleofected with GFP alone) and MLL-AF9–rearranged cells cultured either in liquid or semisolid medium. Retroviral and knock-in indicate transformed human cord blood cells by retroviral MLL-AF9 or MLL-AF9 knock-in. CFC, colony-formed cells; GAPDH, loading control; LC, liquid culture. Numbers below indicate relative MLL-AF9 band intensities compared with WT MLL^N. (C) Representative qPCR analyses show expression levels of MLL target genes compared with control (nucleofected with GFP) at day 65 of culture and human leukemia cell lines. *P < .02. Error bars indicate standard deviation of triplicate analyses. MM6, Mono Mac 6; S1, sample 1; S2, sample 2; WT, wild-type.