Cross-linked chromatin was prepared and sonicated using Bioruptor UCD-200 in ice water bath to generate DNA fragments 200-300 bp in size. Twenty micrograms of each antibody preparation, or 20 µg IgG for mock pulldown controls, were incubated with chromatin prepared from nuclei of approximately 5 million cells. ChIP-seq libraries were generated using KAPA LTP Library Preparation Kits (Kapa Biosystems, KK8232) to yield two independent ChIP replicates for the antibody. We also generated libraries from sonicated genomic input DNA from the same chromatin preparations as controls. Libraries were bar-coded with Bioo Scientific index adapters and sequenced to generate 15-23 million reads per duplicate sample using the Illumina Hi-Seq 2000 instrument at the University of Illinois W.M. Keck Center for Comparative and Functional Genomics according to manufacturer’s instructions.