After 24 h, the cultures were fixed with 1% formalin for 10 min at room temperature, and then the cells were scraped from dishes, washed, collected in a tube and lysed using the lysis buffer containing 1% SDS. Cell lysates were sonicated in a 1–ml vial using COVARIS M220, which produced an average DNA fragment size of approximately 150 bp. The lysate was mixed with streptavidin beads overnight and washed with a series of solutions described in Matsuda K et al. (submitted). The DNA fragments were ligated with adapters and amplified by PCR using TruSeq ChIP Sample Prep Kit (Illumina), according to the manufacturer’s directions, except that we terminated the PCR reaction at 10 cycles.