Cells were fixed with 1% formaldehyde.  Following lysis, chromatin was sheared using a Covaris unltrasonicator.  DNA was pulled down with anti-H3K27me3 antibody. DNA fragments were tagged with Tn5 transposase.  Universal and index adaptor primers were added and DNA was amplified by PCR (NEBNext Ultra II Q5 MasterMix).  DNA was cleaned with Ampure XP beads.