Colonic epithelial cells were isolated as previously described (Roediger et al, 1979, Gut, 20: 484-488). Cells were treated with 1% formaldehyde in PBS for 10 min at room temperature. Cross-linking was terminated by addition of glycine. The cells were spun down and rinsed with ice-cold PBS two times. The cell lysates were sonicated using a Bioruptor (Diagenode) to generate 150–350 bp fragments for immunoprecipitation. h3k27ac antibody (Active Motif, cat no. 39133) was used for ChIP. Libraries were prepared using TruSeq™ RNA Sample Preparation kit (Illumina) following the manufacturer’s instructions. Illumina TruSeq RNA Sample Preparation Kit v1 was used for library preparation.