WT and KO NK cells ( CD3-CD5- NK1.1+ NKp46+) were isolated and flow sorted from spleen and 50,000 of each geneotype were used for transposition in triplicate. ATAC-seq libraries were prepared as described in Buenrostro et al (Buenrostro et al. Transposition of native chromatin for fast and sensitive epigenomic profiling of open chromatin, DNA-binding proteins and nucleosome position. 2013. Nature Methods 10, 1213-1218, doi:10.1038/nmeth.2688