Immediately after sacrificing a mouse with CO2, hair on dorsal skin was removed with an electric razor and Nair Hair Removal cream. After the dorsal skin is isolated from the body, fat and remaining blood vessels were scrapped away. A circular piece of skin was obtained with a 12mm biopsy punch, and minced into tiny pieces. 1x collagenase was then added to the minced skin and the suspension was incubated at 37 °C for 1.5 hours. The suspension is then filtered with a 70μm and a 40μm cell strainers to obtain single cells. SYTOX blue viability dye was then added to the cell suspension and live cells were sorted out using FACS at the UCI Institute for Immunology Flow Cytometry Facility. The Chromium Single Cell 3' v3 (10x Genomics) libraries were prepared and sequenced by University of California Irvine Genomic High Throughput Facility with Illumina NovaSeq6000.