Cells were directly fixed in the cell plate for 10 min with 1% formaldehyde methanol-free and chromatin was prepared for sonication following the Covaris truChIP Shearing kit instructions. Chromatin in Shearing D3 Buffer was sonicated using the Covaris M220 sonicator. Chromatin size distribution was checked using an agarose gel electrophoresis (250-150bp). ChIP-seq libraries were prepared for sequencing using the Illumina TruSeq ChIP Library Preparation Kit.