library_construction_protocol: Cells were fixed with 1% formaldehyde for 10 minutes. After quenching and lysis, chromatin was sonicated using a Covaris S220 focused-ultrasonicator. ChIP was performed using an anti-IRF1 antibody (Santa Cruz, sc-514544). Libraries were prepared using the VAHTS Universal DNA Library Prep Kit for Illumina (ND607) following the manufacturer's instructions.