According to the supplier's manual, total RNA purification was performed using an RNeasy Plus Kit (QIAGEN) with an RNase-free DNase Set (QIAGEN) described in our previous study. In brief, twenty 4um-thick thin sections were cut from cryopreserved skin tissue using a cryostat, dissolved in Lysis Buffers in the RNAeasy Kit to extract total RNA.  The quality and amount of the RNA in each sample were evaluated using Experion (Bio-Rad, Hercules, CA, USA) and NanoDrop (Thermo Fisher Scientific), respectively. For RNA-seq analysis using a next-generation sequencer (NGS), library construction and sequencing for the Illumina HiSeq 4000 was provided as a custom service of Eurofins Genomics K. K. (Tokyo, Japan). The polyA fraction (mRNA) was isolated from total RNA, followed by its fragmentation. Then double-stranded (ds) cDNA was reverse transcribed from fragmented mRNA. The ds cDNA fragments were processed for adaptor ligation, size selection (for 200 bp inserts) and amplification to generate strand-specific cDNA libraries. Prepared libraries were subjected to paired-end 2 x 101 bp sequencing on the HiSeq 4000 platform using HiSeq 3000/4000 SBS Kit (Illumina, San Diego, U.S.)