Lysates were clarified from sonicated nuclei, and histone-DNA complexes were isolated with antibody. Libraries were prepared according to Illumina's instructions. Libraries were prepared according to Illumina's ChIPSeq Sample Prep. protocol (IP-102-1001). Briefly, DNA was end-repaired to produce blunt ends, adenylated for 'A' base addition to the 3' end and then adapter ligated. The adapter ligated DNA was size-selected on an Agarose gel and purified. The purified DNA was enriched by 18 cycles of PCR yielding library fragments of ~290 (insert plus adaptor sequence). The libraries were subjected to hybridisation onto the flowcell for cluster generation and finally sequenced on the Genome Analyzer IIx following the manufacturer's protocols.