BECs were treated with hypotonic solution and mild detergent followed by clarification through sucrose gradient to isolate nuclei. Nuclei were treated with micrococcal nuclease (10U) for 10 minutes at 37°C, re pelleted and supernant containing mononucleosomes stored at 4°C. Mononuclesomal fractions were incubated with 4μg of H3K27ac antibody (Abcam, Ab4729) and 25μL Protein G dynabeads (Life Technologies) in modified RIPA buffer over night at 4°C. Bound complexes were washed and eluted and ChIP DNA extracted using phenol:chloroform/ethanol precipitation. Libraries were prepared using half total volume of eluted ChIP DNA and NEBNext® DNA Library Prep Master Mix Set and Multiplex Oligos for Illumina® (New England Biolabs). Library quality was assessed using Bioanalyzer 2100 High Sensitivity DNA Gels (Agilent).