Phenotypic characterization of the Mll^PTD/− mice. (A) Increased HoxA gene expression in Mll^PTD/− E17.5 FLC. Using real-time RT-PCR, Hoxa7, Hoxa9, and Hoxa10 were shown to be overexpressed in E17.5 FLC from Mll^PTD/− and Mll^PTD/WT embryos compared with both Mll^WT/− and Mll^WT/WT littermate controls. Error bars show standard deviation. Equivalent numbers of (B) c-kit⁺ and (C) CD11b⁺ FLC were sorted with more than 95% purity from Mll^WT/WT, Mll^WT/−, Mll^PTD/WT, and Mll^PTD/− E17.5 embryos. Using real-time RT-PCR, increases in Hoxa9 were measured in Mll^PTD/WT and Mll^PTD/− cells but not in Mll^WT/WT and Mll^WT/− cells. Error bars show standard deviation. (D) ChIP experiments using an anti-H3 dimethylated antibody showed increases in the levels of H3 (Lys4) methylation at the Hoxa9 promoter in both Mll^PTD/WT and Mll^PTD/− FLC compared with Mll^WT/WT and Mll^WT/− controls. Error bars show standard deviation. (E) E17.5 fetal liver hematopoietic progenitor populations were assessed using CFU assays. Mll^PTD/WT mice showed increases in CFU-GM, BFU-E, and CFU-GEMM compared with Mll^WT/WT, while Mll^PTD/− mice showed increases in CFU-GM and BFU-E compared with Mll^WT/WT. Notably, Mll^PTD/− mice showed substantially lower increases in BFU-E compared with Mll^PTD/WT mice. Error bars represent standard error of the means. *P < .05, **P < .01.