The maintenance of MLL leukemic cells is inhibited by disruption of MLL-PAFc. (A) Colony assays were performed with GFP⁺-sorted MLL-AF9, MLL-GAS7, E2A-HLF, and AML-ETO9a cell lines transduced with MigR1 or MigR1-MLLDN. The number of colonies is shown relative to each cell line transduced with empty MigR1 (mean ± SD; MLL-AF9 [n = 4], MLL-GAS7 [n = 2], E2A-HLF [n = 4], and AML-ETO9a [n = 2] independent experiments; **P < .0001, *P < .05 (P > .05); unpaired 2-tailed Student t test). (B) Representative INT-stained plates from the colony assay described in (A) are shown. (C) qRT-PCR was performed for Hoxa9 and Meis1 using RNA isolated from the MLL-AF9 colonies transduced with either MigR1 or MigR1 MLLDN described in (A). Expression is shown relative to the MLL-AF9 cell line transduced with MigR1 (mean ± SD; n = 2 independent experiments; *P < .05, **P < .01; unpaired 2-tailed Student t test). (D-E) Representative colonies from colony assays performed with either the MLL-AF9 or E2A-HLF cell line transduced with MigR1 or MLLDN are shown in both phase contrast and GFP fluorescence. Scale bars = 1 mm. Images were acquired using a 4× lens and Olympus BX-51 microscope with Olympus DP controller software. (F-G) Quantitation of the mean fluorescence from both the MLL-AF9 and E2A-HLF colony assays is shown as determined by flow cytometry performed at the time of sort (precolony) and at the conclusion of the experiment (postcolony, 7 days).