Formaldehyde crosslinked cells were lysed on ice by resuspending and repeated pipetting with 10 cell pellet volumes of RIPA buffer( 50 mM Tris 7.4, 150 mM NaCl, 2 mM EDTA, 0.1% SDS, 0.5% NP-40 and 0.5% deoxycholate).The cells lysates was sonicated to generate DNA fragments of 200-500 bp, centrifuged for 10 min at 12,000 g, and the supernatant was directly used for immunoprecipitation. Place the tube containing the Pierce™ ChIP-grade Protein A/G Magnetic Beads on the magnetic ,then, discard the supernatant. Wash the beads for three times with 1ml 0.1M sodium phosphate Buffer . ChIP-seq was performed by using ThruPLEX® DNA-seq kit (R400427; Rubicon Genomics) according to manufacturer's instructions. The PCR products corresponding to 300-500 bps were gel purified, quantified and stored at -80 oC until used for sequencing. ChIP-Seq sequencing was performed on NextSeq500 platform with 151 bp paired-end sequencing.