Approximately 5 x 10^7 cells were used for each ChIP-Seq assay. The chromatin DNA precipitated by polyclonal antibodies against PHF20L1, EZH2, MTA1, H3K27me2, H3K27me3 or H3K27ac. The DNA was purified with a Qiagen PCR purification kit A Vazyme TruePrep DNA Library Prep Kit V2 for Illumina ® (Vazyme Biotech) was used for DNA library construction. Briefly,the kit uses a new-type transposasea for DNA fragmentation and ligation of Illumina's adapters. After adapter ligation DNA was PCR amplified with Illumina primers for 15 cycles and library fragments of ~250 bp (insert plus adaptor and PCR primer sequences) were band isolated from an agarose gel. The purified DNA was captured on an Illumina flow cell for cluster generation. Libraries were sequenced on the Genome Analyzer following the manufacturer's protocols.