ChIP experiments were performed using 3E6 cells and 4µg a-Mll1 antibody per ChIP (5E7 cells in total) ; 2.5ug a-H3K4me1 and 2.5ug H3K4me3 antibody per ChIP according to standard protocols. For Mll1-ChIP, crosslinking of the cells was performed with dimethyl pimelimidate dihydrochloride (DMP, Sigma-D8388) on the culture plates for 30 minutes. While ChIPed DNA was collected and purified by Qiaquick PCR purification Kit (Qiagen). Libraries were prepared with the Illumina TruSeq protocol according to the manufacturer’s protocol.