Fixed cells were washed and harvested with PBS. Chromatin was prepared by two subsequent extraction steps (10 min at 4°C) with Buffer 1 (50 mM Hepes/KOH pH 7.5; 140 mM NaCl; 1 mM EDTA; 10% Glycerol; 0.5% NP-40; 0.25% Triton) and Buffer 2 (200 mM NaCl; 1mM EDTA; 0.5mM EGTA; 10 mM Tris pH 8). Nuclei were then pelleted by centrifugation, resuspended in Buffer 3 (50 mM Tris pH 8; 0.1% SDS; 1% NP-40; 0.1% Na-Deoxycholate; 10 mM EDTA; 150 mM NaCl) and subjected to sonication with Bioruptor Power-up (Diagenode) yealding genomic DNA fragments with a bulk size of 150-300 bp. Chromatin was precleared with Protein A/G ultralink beads (53133, Pierce) for 2h at 4°C and immunoprecipitation with the specific antibodies carried out overnight at 4°C. Immune complexes were recovered by adding pre-blocked protein A/G ultralink beads and incubated for 2 h at room temperature. Beads were washed twice with Low salt buffer (0.1% SDS; 1% Triton; 2 mM EDTA; 20 mM Tris pH 8; 150 mM NaCl), twice with High salt buffer (0.1% SDS; 1% Triton; 2 mM EDTA; 20 mM Tris pH 8; 500 mM NaCl), once with LiCl wash buffer (10 mM Tris pH 8.0; 1% Na- deoxycholate; 1% NP-40, 250 mM LiCl; 1 mM EDTA) and twice with TE + 50mM NaCl. Beads were eluted in TE + 1% SDS at 65°C and cross-link was reversed O/N at 65°C. The eluted material was phenol/chloroform-extracted and ethanol-precipitated Five to fifteen nanogramms of ChIP DNA or un- enriched whole cell extract (Input) were prepared for sequencing on Illumina Hiseq 2000. We used library kit (Truseq DNA sample prep kit V2, Illumina) with modifications as follows: DNA fragments were repaired to blunt ends, purified with magnetic beads (Agencourt AMPure XP, beckman coulter) and a step of A tailing was performed before Illumina adapters ligation. Two steps of DNA purification on magnetic beads were carried out to eliminate unligated adaptors and then amplified with 15 PCR cycles. To remove unligated left adapters and un- sequenceable large DNA fragments, DNA libraries were selected on E-Gel (2% SizeSelect, Invitrogen) to obtain 280-330 pb DNA fragments (including 130 pb of adapters). Final library was quality checked by DNA high sensitivity chip (Agilent) and for positive target enrichment by qPCR. Quality-controlled samples were then quantified by qPCR and picogreen (Qubit® 2.0 Fluorometer, Invitrogen). Libraries were pooled thanks to various adaptors and qPCR relative measurements. Cluster amplification and following sequencing steps strictly followed Illumina standard protocol.