cells are fixed by 0.8%PFA and lysised in low-salt wash buufer with 0.1% SDS and 1% Triton X-100 CHIP-Seq was performed by New York genome center. DNA was adenylated, ligated to Illumina sequencing adapters, and amplified by PCR (using 10 cycles). Final libraries were quantified using the KAPA Library Quantification Kit (KAPA Biosystems), Next generation sequencing was carried out on an Illumina HiSeq2000 plateform with 50 bp or 100 bp single reads.