To further explore the mechanism how miR-424-5p induced loss of Smad3 promote the proliferation of GC cells both in vitro and in vivo, the TGF-β, Smad3, C-myc, CDK2, CDK4, CDK6 protein levels in GC cells were determined by western blotting. The gene discussed is TGFB1; the disease is gastric cancer.