library_construction_protocol: RNA was isolated by standard Trizol-chloroform extraction according to the manufacturer's instructions mRNA libraries were constructed using Smart-seq2 as previously described. Briefly, 10 ng of total RNA was reverse transcribed using ProtoScript II Reverse Transcriptase (NEB, M0368). After PCR pre-amplification, cDNA libraries were purified using Agencourt Ampure XP beads (Beckman Coulter, A63881) and 2 ng of purified cDNA was used for the next tagmentation reaction. The final amplified libraries were purified again by Agencourt Ampure XP beads and sequenced at 2×150 bp on Illumina NovaSeq 6000 platform.