Genomic DNA was extracted from sub-confluent dishes, fixed and sheared to an average length of 200-1500bp. 10% of the samples from each cell line were pooled to form the Input. RNAPII/BRCA1 antibody was used for immunoprecipitation. ChIP DNA was purified, sheared further to an average length of 350 bp and sequenced after library construction. Sequencing library was prepared using standard Illumina protocols