Cells were crosslinked with 1% formaldehyde for 10 minutes. Then they were washed with PBS and lysed for sonication. Chromatin was precipitated with a specific antibody (anti-H3K4me2, Millipore, 07-030, 2µg/sample; anti-H3K27me3, Millipore, 07-449, 4µg/sample; anti-H3K27ac, Abcam, ab4729, 2µg/sample) and protein A or G-coupled sepharose beads. After elution from the beads, chromatin was decrosslinked and purified using MinElute PCR Purification Kit (Qiagen) according to the manufacturer's instructions. Libraries were prepared via the NEBNext® Ultra™ II DNA Library Prep Kit for Illumina® library preparation protocol according to manufacturer's instructions