Samples with 50,000 cells per condition were shipped in frozen medium (DMEM with 50 % FBS and 10% DMSO) on dry ice to Novogene (Beijing, China). All subsequent processing was performed by Novagene using standard DNA extraction and library preperation protocols All processing was performed by Novagene (Beijing, China). Cell nuclei were isolated, mixed with Tn5 Transposase with two adapters and tagmentation was performed for 30 minutes at 37⁰C. The fragmented DNA was purified and amplified with limited PCR cycle using index primers. Llibraries were prepared according to recommended Illumina NovaSeq6000 protocols.