The ChIP protocol has been adapted from previous studies (Lee et al., 2006; Boyer et al., 2006, Creyghton et al., 2008) with the following modification. Diagenode Bioruptor was used to sonicate with 30 cycles of 30 sec on, 30 sec off. The samples were sonicated in 15ml polystyrene tubes at 4°C while samples were immersed in ice cold water. Antibodies used for ChIP include: ~200 ng of DNA was submitted to SPRI-works Fragment Library System I (Beckman Coulter) for each library prepared. Briefly, the DNA is subjected to size selection (200-400bp) with magnetic beads, end repaired, then a single adenine nucleotide is added to allow for directional ligation of adaptors. For this study, a 1:100 dilution of Single End read adapters (Illumina) was used in the ligation reaction. Each sample was then amplified for 19 cycles, using the Illumina protocol, adding additional bases from the PCR primers that aid sequences to anneal to the Illumina Genome Analyzer flow cell. The samples were then purified on a Qiagen MinElute column, and libraries were quantified by Quant-it DNA Assay (Invitrogen, Q-33120), and examined for proper size and structure by Bioanalyzer (Agilent) and qPCR.