ATAC-seq was performed as previously described with minor modifications (Buenrostro et al., 2013). Fifty thousand cells were pelleted at 550 x g and washed with 1 mL 1x PBS, followed by treatment with 50 μL lysis buffer (10 mM Tris-HCl [pH 7.4], 10 mM NaCl, 3 mM MgCl2, 0.1% IGEPAL CA-630). After pelleting nuclei, the pellets were resuspended in 50 μL transposition reaction with 2.5 μL Tn5 transposase (FC-121-1030; Illumina). The reaction was incubated in a 37°C water bath for 45 minutes. Tagmented DNA was purified using a MinElute Reaction Cleanup Kit (Qiagen) and amplified with varying cycles, depending on the side reaction results. Libraries were purified using a QIAQuick PCR Purification Kit (Qiagen). Libraries were paired-end sequenced (38bp+38bp) on a NextSeq 550 (Illumina). Libraries were validated for quality and size distribution using a TapeStation 2200 (Agilent).