Lysates were clarified from sonicated nuclei and Brd4-DNA complexes were isolated with antibody. ChIP-DNA was end repaired with T4 DNA polymerase and polynucleotide kinase. An A-base was added to the end-repaired DNA fragments. Solexa adaptors were ligated to the ChIP DNA fragments and 200-300bp size fractions were excised from 2% agarose gel stained with GelStar. Adaptor-modified fragments were enriched by 16 cycles of PCR amplification. The DNA library prep was validated in Bioanalyzer for quantity and size.