HeLa cells were fixed with 1% formaldehyde before the DNA was sonicated to a fragment length of 200-600bp with a Bioruptor® (Diagenode, Sparta, NJ). Antibodies were bound to a mix of Protein A and Protein G Dynabeads® (Life Technologies, Grand Island, NY) before an 18 hour incubation at 4°C with the fragmented DNA. DNA was washed and crosslinks reversed before purification with a QIAquick™ PCR purification kit (QIAGEN, Valencia, CA). DNA concentrations were measured using Quant-iT™ PicoGreen® (Life Technologies, Grand Island, NY). A library was constructed from the bound fragments per manufacturer's protocols and the DNA fragments from each independent ChIP were sequenced independently at the UNC High Throughput Sequencing Facility using an Illumina Genome Analyzer II.