title: EdU-seq of untreated hela-s3 in late S phase, replicate 2
design: HeLa cells were collected at 2 or 4 hours after releasing to the S phase while EdU was added 15 minutes before harvesting. Genomic DNA were fragmented by sonication and biotin-labeled by click reaction, then end-repaired and ligated to the adaptor with NEBNext Ultra II DNA library preparation kit according to the manufacturer's instructions. One percent of each sample was reserved for input sequencing. Then, rest samples were purified by streptavidin beads and PCR amplified. Resulting libraries were sequenced by the Illumina NovaSeq system.