ChIP-seq: Cells were crosslinked in 1% formaldehyde at 37C for 10min, quenched with glycine, lysed on ice in buffer containing 1% SDS, diluted to a final concentration of 0.3% SDS and sonicated for 5 minutes total time at ~10W power. Sonicated chromatin was incubated with the relevant antibody overnight at 4C with rotation after dilution to 0.1% SDS. ChIP-seq library prep: Performed as previously described using 5 ng (CTCF and H3K27ac), or 20 ng (H3K9me3) of ChIP DNA input. ChIP-seq sequencing: Paired-end 38 bp reads were generated on a NextSeq500 (Illumina).