50,000 sorted cells were resuspended in nuclear isolation buffer (10 mM Tris-HCl pH 7.4, 10 mM NaCl, 3 mM MgCl2, 0.1% IGEPAL). Nuclei were then treated with Tn5 transposase (Illumina). DNA was isolate using the MinElute Kit (Qiagen) and PCR-amplified using barcoded Nextera primers (Illumina). The DNA libraries were validated using a bioanalyzer (Agilent).