For ChIP-Seq, chromatin was prepared from cells cross-linked with 1% formaldehyde at 37oC for 15 min. Chromatin was fragmented by sonication and the ChIP DNA was blunt-ended, ligated to the Solexa adaptor and amplified using adaptor primers for 17 cycles. Fragments around 200bp were isolated from agarose gel and purified DNA was used directly for cluster generation and sequencing following the manufacturer protocols.