library_construction_protocol: cells were firstly crosslinked with 1% paraformaldehyde. After addtion of glycine solution , cells were lysed with cell lysis buffer and nuclear lysis buffer. The purified DNA was used for ChIP-seq library preparation. The library was constructed by NovogeneCorporation (Beijing, China). Subsequently, pair-end sequencing of sample was performed on Illuminaplatform (Illumina, CA, USA). Library quality was assessed on the Agilent Bioanalyzer 2100 system.