K562 cells were lysed with lysis buffer containing 0.1% NP-40, 0.1% Tween-20 and 0.01% digitonin. ATAC-seq libraries were prepared using the Hyperactive ATAC-Seq Library Prep Kit for Illumina from Vazyme. The purified DNA was end-repaired and then ligated with adapters. After purified by AMPure XP beads from Beckman, the DNA was amplified using 15 cycles with the PCR program.