For FAIRE: Nuclei of formaldehyde crosslinked cells were isolated, lysed and sonicated. Accessible DNA was isolated from the clarified lysates by phenol-chloroform extraction. For ChIP-seq: Nuclei of formaldehyde crosslinked cells were isolated, lysed and sonicated. H3K27ac-DNA complexes were isolated from the clarified lysates with antibody against H3K27ac. For RNA-seq: RNA from harvested cells were column purified with Purelink RNA Mini kit (12183025, life technologies). Libraries were prepared according to Illumina's instructions.