Cells were fixed at room temperature with 2mM disuccinimidyl glutarate (DSG) for 30min before an additional fixation with 1% formaldehyde for 15min and quenched with glycin. Between 5 and 15 million cells were used for each ChIP-seq. Cell lysates were sonicated using a BioRuptor Standord or BioRuptor Pico and then immunoprecipitated using antibodies bound to a 2:1 mixture of Protein A Dynabeads and Protein G Dynabeads. For ChIP-seq, HUVECs were fixed with DSG for 30 min, then formaldehyde for 15 minutes and quenched with glycine. Lysates were sonicated, a small fraction of chromatin was removed and prepared as inputs, whereas the remaining complexes were immunoprecipitated with antibody. For ChIP-seq, double-stranded End Repair was performed and inserts were ligated to barcoded  BioO Nextflex adapters and amplified prior to sequencing.