Cells were crosslinked with formaldehyde treatment and chromatin fragmented to 200-300 bp by sonication. ChIP material was blunt-ended and phosphorylated with the End-it-Repair kit (EPICENTRE). Illumina genome sequencing adaptors were ligated with T4 DNA ligase (New England Biolabs) after addition of adenosine nucleotides, using exo-Klenow. Samples were PCR amplified with multiplexed Illumina genomic DNA sequencing primers. PCR products (250 to 450 bp in size) were gel-purified and submitted for Illumina deep sequencing.