Initial proteomic analysis of the secretome of two NSCLC subtypes, A549 (adenocarcinoma) and SK-MES-1 (squamous cell carcinoma), detected several secreted proteins with a potential role in tumour development or metastasis i.e. CC, CL, IGFBP-7, VEGF-A and TNF-α. This evidence concerns the gene TNF and squamous cell carcinoma.