library_construction_protocol: Total RNA from mouse forepaws was extracted using the RNeasy Kit and RNase-Free DNase Set (Qiagen) and used for library preparation and sequencing. Samples were barcoded with CEL-seq primers during a reverse transcription and pooled after second strand synthesis. The resulting cDNA was amplified with an overnight in vitro transcription reaction. From this amplified RNA, sequencing libraries were prepared with Illumina Truseq small RNA primers. Single-cell mRNA seq protocol of CEL-Seq. Paired-end sequencing was performed on the Illumina Nextseq500 platform