The cells were crosslined by 1% Formaldehyde for 10 minites. After the crosslink was quenched by 125mM Glycine. Then the chromatin was fragmented by sonication. The chromatin was subjected pull down by specific antibodies respectively as indicated. The DNA was eventually extracted after the de-crosslinking and Phenol-choloroform extraction. ChIP-seq library was constructed according the the protocol provided by the NEBNext® ChIP-Seq Library Prep Master Mix Set for Illumina® kit.