The aim of this study was to investigate the consequences of insulin-like growth factors (IGF) and IGF receptor dysfunction in lung carcinomas. A correlation between increased expression (at mRNA and protein levels) for IGF-1 and IGF-1R and decreased apoptosis were found in large-cell carcinomas and adenocarcinomas. In 40% of informative adenocarcinomas expressing the highest values of IGF-2 and Ki-67 proteins, M6P/IGF-2R gene had LOH at one allele and a mutation in another allele. All four squamous cell carcinoma samples expressed LOH/mutation in the M6P/IGF-2R gene. The alphaIR3 strongly diminished proliferation and increased apoptosis in cultures established from squamous cell carcinomas overexpressing IGF-2 and IGF-1R. Telomerase activity was assessed in four squamous cell carcinomas. Cell treatment with IGF-1 increased telomerase activity. The opposite was observed when the cells were treated with alphaIR3, which inhibits the activity of IGF-1 receptors. Our findings suggest that disruption of the IGF/IGF receptors axis is involved in lung cancer formation.