Cells were crosslinked with formaldehyde, lysed and DNA was fragmented into pieces of average 300bp by sonication. Chromatin was precipitated with a specific antibody and protein A-coupled sepharose beads. After elution from the beads, chromatin was decrosslinked and purified via QIAquick PCR Purification Kit according to the manufacturer's manual. Library preparation for ChIP analysis was performed with the NEBNext® Ultra™ DNA Library Prep Kit for Illumina® (Catalog #E7370) according to the manufacturer’s protocol. No size selection was used and amplification was performed using 10 PCR cycles.