STK11 and metastatic malignant neoplasm in the lymph nodes: Considering all of the above factors, we performed a comprehensive retrospective study in a large series of patients with resectable (stage I-IIIA) NSCLC with the aim of performing an in situ immunohistochemical evaluation of the incidence of loss of LKB1 expression in surgical specimens of NSCLC patients with and without lymph node metastasis, including all of the various histotypes, in order to elucidate possible patterns of expression and characteristics of the LKBl-less phenotype and to identify potential correlations of prognostic significance.