For ATAC-seq analysis using the Illumina NextSeq500, ~50,000 cells were processed for tagmentation followed by DNA isolation and library generation. Raw reads that aligned to exactly one location in the reference mouse genome (mm9) were retained for downstream data analysis. Following protocols established by Buenrostro et al. (Curr Protoc Mol Biol. 2015 Jan 5;109:21.29.1-9)