library_construction_protocol: Total RNA was extracted by customer following the manufacturer's instructions and checked for a RIN number to inspect RNA integrity by an Agilent 2100 Bioanalyzer (Agilent technologies, Santa Clara, CA, US).Qualified total RNA was further purified by RNAClean XP Kit (Cat A63987, Beckman Coulter,Inc.Kraemer Boulevard Brea, CA,USA)and RNase-Free DNase Set  (Cat#79254, QIAGEN, GmBH, Germany) For 10 × library preparation, each cDNA molecule was tagged on the 3'end of a mRNA transcript with unique molecular identifiers (UMI) and cell labels indicating its cell of origin on cDNA synthesis.