library_construction_protocol: exosomal RNA were extracted with exosome RNA Purification Kit; molm-13 RNA was extracted with TRIzol. Ribosomal RNA (rRNA) was removed from the sample using the GenSeq® rRNA Removal Kit (GenSeq, Inc.). After removal of rRNA from samples, library construction was completed using GenSeq ® Low Input RNA Library Prep Kit (GenSeq, Inc.) in accordance with the manufacturers construction. The fragmented mRNA was reversed into cDNA and then, E. coli DNA polymerase I (NEB, cat.m0209, USA) and RNase H (NEB, cat.m0297, USA) are used for double strand synthesis, dUTP Solution (Thermo Fisher, cat. R0133, CA, USA) was added to the double-stranded DNA, The two chains were digested with UDG enzyme (NEB, cat.m0280, MA, US), to form a fragment size of 300bp±50bp library (chain specific library).