library_construction_protocol: CAR-T cells were harvested using TRIzol (Invitrogen) after each round of NALM-6 stimulation. RNA was extracted using RNeasy Plus mini isolation kit (Qiagen). mRNA library preparations were performed using a NEBNext® Ultra™ RNA Library Prep Kit for Illumina and samples were multiplexed using barcoded primers provided by NEBNext® Multiplex Oligos for Illumina® (Index Primers Set 1). Libraries were sequenced with Novaseq systems (Illumina).