Approximately 50,000 cells were washed once with PBS and once with cold lysis buffer (10 mM Tris-HCl, pH 7.4, 10 mM NaCl, 3 mM MgCl2, 0.1% IGEPAL CA-630). Cells were then suspended in 50 µl 1X reaction buffer (25μl Tagment DNA Buffer, 2.5μl Tagment DNA enzyme I, and 22.5μl water) (Nextera DNA Library Preparation Kit, Illumina). Transposase reactions were carried out at 37°C for 30 minutes and immediately DNA was purified using ChIP DNA Clean & Concentrator kits (Zymo Research). DNA was amplified using the Nextera primer Ad1 and a unique Ad2.n barcoding primer using NEBNext High-Fidelity 2XPCR Master Mix (NEB) for 14 cycles. Resulting libraries were size selected by gel excision to 175-225 bp and purified.