~10^5 cells were resuspended in lysis buffer and chromatin was sonicated to 200-500 bp with Covaris M220 system. Then, the sonicated chromatin was immunoprecipitated with the antibodies. Antibodies used in ChIP assays were Esrrb, H3k4me1, H3k4me2, H3k4me3 and H3k27ac. ChIP DNA was reverse-crosslinked, eluted, and purified by phenol-chloroform-isoamyl alcohol extraction, followed by ethanol precipitation. For sequencing, 10–100 ng DNA was used for library preparation following the New England Biolabs library preparation protocol.