Chromatin from formaldehyde fixed cell (2x107 cells per ChIP) was fragmented to a size range of 160-480 bp using a combination of micrococcal nuclease digestion and sonication with Bioruptor (Diagenode). Solubilized chromatin was immunoprecipitated with antibody. To generate libraries for Illumina high-throughput sequencing of ChIP and input DNA, end repair, adenylation, ligation with indexed adaptors, and 18 cycles of PCR with Illumina primers were performed following the TruSeq ChIP Sample Preparation guide (Illumina).