Cells were harvested and washed with PBS before a 2-step crosslinking procedure. First, proteins were crosslinked by incubating cells for 45min at RT in PBS supplemented with 0.83 mg/ml Di(N-succinimidyl) glutarate (DSG, Sigma). Cells were then washed 4 times with PBS, prior to formaldehyde crosslinking of proteins and DNA for 10min at RT using 1% formaldehyde (Pierce) in IMDM with 10% FCS. Formaldehyde was quenched by adding 1/10th volume 2M glycine and crosslinked cells were washed twice in ice-cold PBS. For samples to be used for histone modification ChIP, single crosslinking with 1% formaldehyde was performed. Nuclei were prepared essentially as described in Lefevre et al 2003, sonicated using a Bioruptor water bath in immunoprecipitation buffer I (25 mM Tris 1 M pH 8.0, 150 mM NaCl, 2 mM EDTA pH 8.0, 1% TritonX-100 and 0.25% SDS) {Lefevre, 2003 #45}. After centrifugation the sheared 0.5-2 kb chromatin fragments (1-2 x 106 cells) were diluted with 2 volumes immunoprecipitation buffer II (25 mM Tris pH 8.0, 150mM NaCl, 2 mM EDTA pH 8.0, 1% TritonX-100, 7.5% glycerol). Immunoprecipitation was carried out for 2-4 hours at 4°C using 2 μg antibody coupled to 15 μl Protein-G dynabeads (Invitrogen), with the exception of the H3K79me2 and the H4K5Ac antibodies where immunoprecipitation was carried out overnight. Following IP, the beads were washed with low salt, high salt, LiCl and Na/TE buffers before crosslinks were reversed overnight. DNA was extracted using Ampure beads (Beckman Coulter) and qPCRs were performed to validate ChIP quality. ChIP-seq libraries were prepared using the Kapa Hyper Prep kit for Illumina platforms according to manufacturer’s instructions