Chromatin immunoprecipitation (ChIP) was performed as described previously described (PMID: 23508109), with the following modifications: cross-linking was performed by adding methanol-free 16% formaldehyde directly to the culture media to a final concentration of 1% and incubating for 5 minutes at room temperature with gentle rocking; samples were subsequently sonicated with a Diagenode Bioruptor at high power in 30-second bursts separated by 30-second incubations in ice water for a total of 23 cycles. A minimum of 1 ng DNA from ChIP samples were used to prepare libraries using the Nugen Ovation Ultralow System V2 1-16 Part No. 0344 according to the manufacturer’s instructions. Samples were run on an Illumina HiSeq using 1X50 bp end reads