Total inputs and ChIPed samples were prepared for libraries using 10ng of material. Aliquots of the samples were tested in qPCR using the KAPA SYBR FAST qPCR Master Mix (KAPA Biosystems, KK4604) to determine the optimal number of PCR cycles needed to amplify each library without reaching saturation. Libraries were amplified with KAPA HiFi Hotstart Readymix polymerase (KAPA Biosystems, KK2602), size-selected using Ampure XP beads (Beckman Coulter) and always quality checked on Bioanalyser DNA high sensitivity chip (Agilent) and quantified by picogreen (Qubit® 2.0 Fluorometer, Invitrogen). Chromatin was prepared from 10 million cells as previously described (Rowe et al., 2013b).