Cells were fixed in 1% formaldehyde for 10 min, quenched with glycine and washed 2 times with PBS. Cells were then resuspended in lysis buffer and sonicated to shear the chromatin to an average length of 600 bp. Supernatants were precleared with Protein-A/G Dynabeads (Invitrogen) and 10% input was collected. Immunoprecipitations were performed with antibodies to H3K4me3 and H3K27me3 (Millipore). DNA-protein complexes were pulled down using Protein-A/G Dynabeads (Invitrogen) washed. DNA was recovered by overnight incubation at 65°C to reverse crosslinks and purified using QIAquick PCR purification columns (QIAGEN). Libraries were prepared from ChIP DNA experiments with the TruSeq® DNA LT/HT Sample Prep Kit (Illumina) following manufacturer’s instructions.