ChIP-seq: Cells were lysed in RIPA buffer (10 mM Tris-HCl pH 8.0, 140 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.1% SDS, 0.1% sodium deoxycholate) supplemented with protease inhibitor (details see Yan et al). Hi-C and 4C-seq: Briefly, 2 million cells were cross-linked with 1% formaldehyde for 10min at RT and reaction was quenched using 125 mM of Glycine for 5 min at RT. Nuclei were isolated and directly applied for digestion using 4 cutter restriction enzyme MboI (NEB) at 37 °C o/n. All libraries were constructed using standard illumina TruSeq LT library prep.