PECAM1 and lung adenocarcinoma: Immunohistochemical characterization of six tumor regions was done for ALK and markers of lung adenocarcinoma (NKX2.1), epithelial (E‐cadherin, pan‐cytokeratin, and cytokeratin 18) and mesenchymal (vimentin) phenotypes, tumor vasculature (CD31), and basement membrane organization (collagen type IV).