NPC were crosslinked in 1% formaldehyde for 10 min at room temperature. Crosslinking was quenched with 0.125 M glycine for 5 min. Pelleted cells were lysed in 1 ml ChIP buffer and sonicated for 12 min in a Bioruptor. ChIP-Seq experiments were performed as previously described (Morey et al, Cell Stem Cell. 2012, 10: 47-62) It was performed using the NEBNext DNA Sample Prep Reagents Set 1