HeLa cells transiently expressing Flag-Za or Flag-Zaa were cross-linked with 1% formaldehyde for 10 minutes at room temperature and cross-linking was quenched with 137 mM glycine. After nucleus extraction, isolated nucleus pellets were resuspended in Sonication buffer (50mM HEPES [pH7.9], 140mM NaCl, 1mM EDTA, 1% triton X-100, 0.1% Na-deoxycholate, 0.1% SDS, 1X protease inhibitor). The chromatin was sonicated to the range of 100-300 bp, and then immunoprecipitated overnight using an anti-Flag antibody (Sigma, USA). Sequencing libraries were manually generated for high-throughput sequencing. Either end of DNA strands was filled using the Epicentre DNA END-Repair kit (Epicentre Biotechnologies, Madison, WI). Adenine was added at 3' ends by Taq DNA polymerase (New England Biolabs, Beverly, MA) under dATP conditions. Illumina's adaptor oligomers was ligated at both ends using Quick Ligation kit (Qiagen, Germantown, MD). After purified twice, DNA libraries are amplified using Solexa primers (Illumina, San Diego, CA) and Phusion PCR master mix (Thermo Scientific, Hudson, NH).