design: About 100,000 cells were subjected to ATAC-seq experiment following the Omni-ATAC protocol (PMID: 28846090). The libraries were purified by AMPure XP magnetic beads with double size selection (0.55X and 1.35X). Size distribution of library DNA was determined by Fragment Analyzer (Advanced Analytical Technologies, IA) using the High Sensitivity NGS Fragment Analysis Kit (Cat# DNF-486).