ChIP-seq: Cells were chemically cross linked by 1% formaldehyde. Cell lysates were made by appropriate sonication and protein-DNA complexes were isolated with antibody. ChIP-seq: Libraries were prepared according to Illumina's instructions. Briefly, DNA was end-repaired and the blunt, phosphorylated ends were treated with Taq polymerase and dATP to yield a protruding 3- 'A' base for ligation of Illumina's adapters which have a single 'T' base overhang at the 3’ end. After adapter ligation, DNA was PCR amplified with Illumina primers for 15 cycles and library fragments of ~250 bp (insert plus adaptor and PCR primer sequences) were band isolated from an agarose gel. The purified DNA was captured on an Illumina flow cell for cluster generation. Libraries were sequenced on HiSeq 2000 or 2500 following the manufacturer's protocols.