Caveolin-1 expression is down-regulated in oncogenically transformed fibroblasts as well as in breast and lung carcinoma cell lines. In the present study, we studied by immunohistochemistry the expression of caveolin-1 and caveolin-2 proteins in primary non-small cell lung tumors of human origin. All tumor specimens tested were negative for both caveolins in patients who had not undergone neoadjuvant therapy prior to surgery (32 of 32 patients). Both caveolin-1 and caveolin-2 were abundantly expressed in the tissue surrounding the tumors. Fibroblasts, alveolar epithelial cells, smooth muscle cells, and endothelial cells were all positive for caveolins. In order to better understand the potential effects on lung cancer cells of this caveolin induction, we expressed caveolin-1 complementary DNA in a lung adenocarcinoma cell line (Calu-6). In cancer cells overexpressing caveolin-1, proliferation was strongly reduced. We also observed a sharp decrease in cell motility after caveolin-1 expression in Calu-6 cells. However, no changes were observed in terms of sensitivity to cytotoxic drugs.