Live cells were crosslinked with 1.8% formaldehyde for 10 min at 25°C and soluble chromatin prepared as described in Schwartz et al., 2006. Libraries were prepared according to Illumina's instructions from TruSeq ChIP Sample Preparation Kit with some modifications. Indexed adaptors from TruSeq ChIP Sample Prep Kit were used for barcoding. After adapter ligation, 250-500bp size was selected by gel size selection, and the subsequent amplification was done with 15 cycles. With the constructed libraries, 100bp paired-end sequencing was performed by Illumina HiSeq technology