MEF2D is transcriptionally regulated by DOT1L and HOXA9 in MLL-r AML. (A) RT-qPCR analysis of MEF2D, CEBPE, and HOXA9 in MOLM-13 cells post 4-day treatment of 1 µM SGC0946 or dimethyl sulfoxide (DMSO). (B) Western blot analysis of MEF2D and CEBPE protein levels in MOLM-13 cells post 4-day treatment of 1 µM SGC0946 or DMSO. (C) BRD4 ChIP-seq data profile in MV4-11 cells treated with DMSO or 5 µM SGC0946 DMSO (GSE71776). (D) HOXA9, H3K27ac, and H3K4me1 ChIP-seq profile in HOXA9/MEIS1-transformed leukemia cells (GSE103446). (E) Western blot analysis showing MEF2D and CEBPE protein levels in control- or Hoxa9- overexpressed MOLM13 cells post 4-day treatment of 1 µM SGC0946 or DMSO. (F) Relative expression levels of HOXA9, MEF2D, and CEBPE in TCGA AML patient samples with low (n = 41, red) and high (n = 124, blue) HOXA9 expression. Boxplots show medians and interquartile ranges, whiskers represent the lowest and highest observations. Data were analyzed by Mann-Whitney U test. (G) Western blot analysis showing MEF2D and CEBPE protein levels in control- or MEF2D- overexpressed MOLM13 cells post 4-day treatment of 1 µM SGC0946 or DMSO. (H) Wright-Giemsa of control- or MEF2D- overexpressed MOLM-13 cells post 6-day treatment of 1 µM SGC0946 or DMSO. (I-J) Flow cytometry analysis of control- or MEF2D-overexpressed MOLM-13 cells post 6-day treatment of 1 µM SGC0946 or DMSO. (K) Growth of control- or MEF2D-overexpressed MOLM-13 cells post 6-day treatment of DMSO or indicated doses of SGC0946. **P < .01; ***P < .001.