To investigate the impact of miR-let-7a on PKM2 levels in GC cell lines, we used lentiviral transfection to construct miR-let-7a overexpression (pre-miR-let-7a) and knockdown (miR-let-7a-inhibitor) GC cell lines including SGC-7901 and BGC-823. The gene discussed is PKM; the disease is gastric cancer.