We validated the expression of OPN and EMT‐related proteins (e.g., E‐cadherin, vimentin) in 208 non‐small‐cell lung cancer (NSCLC) tumors and the adjacent nontumorous tissues, further to explore the function of OPN in the progression of lung cancer, with a focus on a potential communication between OPN and EMT in the lung cancer. The gene discussed is CDH1; the disease is lung cancer.