50x10^6 cells were collected by trypsinisation, resuspended in complete media and fixed with 1% formaldehyde. Chromatin isolated from fixed nuclei was sonicated and incubated at 4C overnight with Protein A Dynabeads (Invitrogen) coated with 10ug of anti-Ezh2 antibody (Diagenode). Further steps were carried out according to Seitan et al Nature (2011). Single read high throughput sequencing libraries were prepared from 10ng of ChIP DNA using Illumina ChIP-Seq Sample Prep. Kit and sequenced according to the manufacturer's protocols using Illumina Hiseq 2500