library_construction_protocol: Gastric cancer cells were grown in 6-well plates and transfected with NC siRNAs and the ELF3-AS1-targeted siRNAs. After 48 hours, remove the medium and directly add 800μL Trizol into the 6-well plate to harvest samples. Total RNA was extracted using Trizol reagent (Invitrogen, USA) according to the manufacturer's instructions. The RNA purity and concentration was checked using the NanoPhotometer spectrophotometer (IMPLEN, CA, USA). Oligo(dT)-attached magnetic beads were used to purified mRNA. Purified mRNA was fragmented into small pieces with fragment buffer at appropriate temperature. Then First-strand cDNA was generated using random hexamer-primed reverse transcription, followed by a second-strand cDNA synthesis. afterwards, A-Tailing Mix and RNA Index Adapters were added by incubating to end repair. The cDNA fragments obtained from previous step were amplified by PCR.