In this study, we demonstrate that hypoxia significantly enhances GRPR expression in SCLC cell lines, COR-L24 and DMS79, as confirmed by Western blot, immunofluorescence, and flow cytometric analysis of binding with fluorescein isothiocyanate–labelled bombesin (BBN-FITC), a known GRPR ligand. This evidence concerns the gene GRPR and small cell lung carcinoma.