HepG2 and S2 cells were fixed in 1% methanol-free formaldehyde (Thermo Scientific, 28906) in D-MEM (for HepG2 cells) or Express Five SFM (for S2 cells) for 15 min at room temperature under gentle shaking. Formaldehyde was quenched for 5 min by adding 125 mM glycine final concentration. Cells were rinsed twice with ice-cold PBS, harvested by scraping (HepG2) and pelleted (300 g, 10 min, 4 °C). Cells were processed according to RELACS / AutoRELACS protocols Libraries were prepared according to Illumina's instructions using NebNext Ultra II kit. After Illumina adapter ligation, library was PCR amplified. Fragments were size-selected to eliminate adapter dimers contamination using AMPure XP beads. The purified DNA was captured on an Illumina flow cell for cluster generation. Libraries were sequenced on NovaSeq 6000 machine, following manufacturer's protocol. High-throughput RELACS ChIP-seq and automated high-throughput AutoRELACS ChIP-seq