ChIP samples harvested after 1% formaldehyde fixation for 12 minutes, sonicated, processed and ChIP-enriched via standard protocols (Active Motif ChIP-IT HS kit) with H3K27ac pAb cat. #39133. ChIP enriched DNA was treated with Proteinase K at 55 ˚C for 30 minutes followed by reversal of crosslinks by heating to 80 ˚C for 2 hours, and DNA purification by column (MiniElute PCR purification kit, Qiagen). DNA was extracted from ChIP-seq samples prepared following the Active Motif ChIP-IT High Sensitivity kit protocol. Standard Illumina barcodes were introduced during library preparation with the Illumina TruSeq ChIP Sample Prep Kit 48 Samples - Set A Cat# IP-202-1012