Cells were fixed in DMEM containing 10 mM Hepes, pH 7.6, 1% formaldehyde, 15 mM NaCl, 0.15 mM EDTA and 0.075 mM EGTA, for 10 min at room temperature. The reaction was quenched with 0.125 M glycine for 5 min at room temperature, cells were washed with PBS and lysed in 50 mM Hepes, 140 mM NaCl, 1 mM EDTA, 10% glycerol, 0.5% Igepal CA630 and 0.25% Triton X-100. After centrifugation, isolated nuclei were washed once in 10 mM Tris pH 8.0, 200 mM NaCl, 1 mM EDTA and 0.5 mM EGTA, then resuspended in 10 mM Tris, pH 8.0, 1 mM EDTA, 0.5 mM EGTA and 0.5% N-Lauryl Sarcosine, and sonicated using a Diagenode Bioruptor to an average chromatin size of 200 bp. Libraries were prepared according to manufacturer’s instructions (Illumina). Immunoprecipitated DNA was first end-repaired using End-It Repair Kit (Epicenter), tailed with an A using Klenow exo minus (NEB M0212), and ligated to custom adapters with LigaFast (Promega, city, state #M8225). Fragments of 300±50 bp were size-selected and subjected to ligation-mediated PCR amplification (LM-PCR), using Phusion DNA polymerase (NEB M0530).