LSD1 inhibition with GSK-LSD1 is C/EBPα-dependent. (A) Colony formation assay from WT or C/EBPα KO MLL-AF9 leukemia cells treated with vehicle or GSK-LSD1. n = 3. (B) Morphology of 1° CFU colonies derived from WT (left) or C/EBPα KO cells (right) treated with vehicle (top) or GSK-LSD1 (bottom). Bar, 0.5 mm. n = 3. (C) CFU assay with colony morphologies upon GSK-LSD1 treatment in WT and C/EBPα KO cells (BFU-E, burst-forming unit-erythroid; CFU-E, colony forming unit-erythroid; G, granulocyte; GEMM, granulocyte/erythrocyte/macrophage/megakaryocyte; GM, granulocyte/macrophage; M, macrophage). n = 3. (D) Representative morphology of cells from CFU assay with GSK-LSD1 treatment. Scale bar, 10 µm. (E) CFU assay with colony types after treatment with vehicle or GSK-LSD1 in C/EBPα^fl/fl+MIT empty vector and C/EBPα^fl/fl+MIT-Cre leukemia cells. n = 3. (F) Representative morphology of cells from 1° CFU assay from WT or C/EBPα-excised MLL-AF9 leukemia cells treated with 0.5 µM GSK-LSD1. Scale bar, 5 µm. (G) GFP engraftment in the BM of leukemic mice engrafted with WT or C/EBPα KO MLL-AF9 cells treated in vivo with vehicle or GSK-LSD1 for 2 weeks. n = 5. (H) Bar graphs representing spleen weights from leukemic mice engrafted with either WT or C/EBPα KO MLL-AF9 leukemia cells treated in vivo with vehicle or GSK-LSD1 for 2 weeks. n = 3.