cells were fixed with 1% para-formaldehyde (Electron Microscopy Sciences) for 30 minutes at room temperature. ChIP assays were performed following previously described conditions: chromatin sonication and immunoprecipitation in lysis buffer (50mM Tris–HCl pH=8, 140mM NaCl, 1mM EDTA, 1% Triton, 0.1% Na-deoxycholate) complemented with protease inhibitor cocktail (Roche 11873580001); 2x washes with lysis buffer; 2x washes with lysis buffer containing 500mM NaCl; 2x washes with washing buffer (10mM Tris–HCl pH=8, 250mM LiCl, 0.5% NP-40, 1mM EDTA, 0.5% Na-deoxycholate); 2x washes with 1x TE buffer; elution at 65°1C; 15 min at 65°C in elution buffer (50mM Tris–HCl pH=8, 10mM EDTA, 1% SDS); overnight decrosslinking at 65C followed by PCI purification. qPCR-qualified ChIP assays were quantified (Qubit dsDNA HS assay kit; Invitrogen); 10 ng of the ChIPed material was used for preparing Illumina sequencing libraries. Libraries were prepared following a multiplexing approach (NEXTflexTM ChIP-seq Bioo Scientific kit; ref: 5143-02).