The regulatory influence of PTTG1 on the TGF-β/Smad pathway was analyzed by measuring the expression levels of TGF-β, Smad2, Smad3, and their phosphorylated forms.<h4>Results</h4>PTTG1 expression was significantly upregulated in gastric cancer tissues compared with normal gastric mucosa according to TCGA data and validation in cell lines. The gene discussed is SMAD3; the disease is gastric cancer.