Lysates were clarified from sonicated nuclei and histone-DNA complexes were isolated with antibody. Total RNA was isolated from K562 cells using the RNAeasy kit (Qiagen # 74104) and treated with RNase-Free DNase Set (Qiagen # 79254) to remove genomic DNA, according to the manufacturer’s instructions. ChIP DNA, input DNA or cDNA were subject to end repair, A-tailing, adaptor ligation and cleavage with USER enzyme, followed by size selection to 250-500 bp and amplification with NEBNext sequencing primers. Libraries were purified, quantified, multiplexed and sequenced with 1x75bp single-end reads on an Illumina NEXT-seq (Stanford Functional Genomics Facility).