Cells were double fixed with DMA followed by formaldehyde. Following lysis and resuspension in RIPA buffer containing 0.1% SDS, cells were sonicated using a Bioruptor Pico (Diagenode). Chromatin was pre-cleared with pre-blocked protein A and G beads overnight prior to incubation with 1ug of antibody. Beads were washed, decrosslinked, treated with proteinase K and then purified using a QIAquick PCR kit (Qiagen). Libraries were constructed using NEBNext Ultra DNA library prep kit according to the manufacturer's instructions.