Live cells were crosslinked with 1.8% formaldehyde for 10 min at 25C and soluble chromatin prepared as described in Schwartz et al., 2006. ChIP was done as described in Schwartz et al., 2006. Libraries were prepared using NEBNext ChIP-Seq Library Prep Master Mix Set and Multiplex Oligos for Illumina (New England BioLabs) following the manufacturer instructions.