The ATAC-seq protocol was performed as previously described (Buenrostro et al., 2013; Ludwig et al., 2019). Briefly, cell samples were thawed and 50,000 cells were washed twice in PBS. Pelleted cells were then directly transposed using an all-in-one transposition buffer (Tris pH 7.5, MgCl2, DMF 5%, PBS 0.3X, NP-40 0.1%, Illumina Tn5 1X, ddH20 to 50 uL). The transposition reaction was completed with thermomixing at 37°C for 30 minutes at 300 rpm on a thermoshaker. Transposed DNA was purified with MinElute column clean-up (Qiagen), then minimally amplified for sequencing as previously described (Buenrostro et al., 2015). Prepared libraries were purified with MinElute column clean-up (Qiagen) and digested with ExoI (NEB). Libraries were quantified with a Qubit dsDNA HS Assay kit (Invitrogen).