NCI-H69 cells were crosslinked with 1% formaldehyde for 10 min at room temperature and quenched with glycine. Chromatin was sheared to 200-500 bp fragments. Immunoprecipitation was performed with anti-RBBP4 antibody (Abcam, ab79416; ChIP 1:100) or anti-P300 antibody (Abcam, ab275378; ChIP 1:100) and Protein A/G magnetic beads overnight at 4°C; input DNA was processed in parallel. Immunocomplexes were washed, reverse-crosslinked at 65°C for 8 h, digested with proteinase K, and ChIP DNA was purified. ChIP DNA libraries were generated by end repair, A-tailing, adapter ligation, size selection of 250-350 bp fragments, and PCR amplification. Libraries were sequenced as paired-end 150 bp reads on an Illumina NovaSeq 6000 platform by Wuhan Kangce Biological Technology Co., Ltd.