library_construction_protocol: Cells were crosslinked in 1% formaldehyde (Pierce #28908) for 10 minutes, quenched with 125 mM glycine (Sigma #G8898) for 5 minutes, washed with cold PBS, and collected by scraping. Nuclei were isolated in Farnham lysis buffer (5 mM PIPES pH 8.0, 85 mM KCl, 0.5% NP-40) with protease inhibitors, then lysed in ChIP lysis buffer (1% SDS, 10 mM EDTA, 50 mM Tris-HCl pH 8.1). Chromatin was sheared (Diagenode Bioruptor Plus) for 15 cycles (30 sec on/off) to 200-500 bp fragments. Chromatin (50 µg per IP) was diluted in ChIP dilution buffer (0.01% SDS, 1.1% Triton X-100, 1.2 mM EDTA, 16.7 mM Tris-HCl pH 8.1, 167 mM NaCl) and incubated overnight at 4°C with 6 µg anti-FLAG M2 (Sigma #F1804) and 40 µL Dynabeads Protein G (ThermoFisher Scientific #10004D). Beads were washed sequentially with low salt buffer (0.1% SDS, 1% Triton X-100, 2 mM EDTA, 20 mM Tris-HCl pH 8.1, 150 mM NaCl), high salt buffer (same with 500 mM NaCl), LiCl buffer (0.25 M LiCl, 1% NP-40, 1% sodium deoxycholate, 1 mM EDTA, 10 mM Tris-HCl pH 8.1), and twice with TE buffer (10 mM Tris-HCl pH 8.0, 1 mM EDTA). Chromatin was eluted in 1% SDS, 100 mM NaHCO₃ at 65°C for 30 minutes. Crosslinks were reversed overnight at 65°C, followed by RNase A and Proteinase K treatment. DNA was purified using the phenol:chloroform:isoamyl alcohol. The sequencing library was prepared from 11.5 ng of purified DNA using the Accel-NGS 2S Plus DNA Library Kit (Swift Biosciences # 21096)