In this study we have investigated a panel of lung-cancer cell lines, both of small-cell carcinoma and non-small-cell type, for the expression of receptors for platelet-derived growth factor. Although we found mRNA expression for the beta-type receptor on one small-cell and one non-small-cell line and alpha-type receptor mRNA expression on one small-cell-cancer cell line, only the beta receptors of the non-small-cell line (H-157) proved to be functional. Thus, the cell line H-157 displayed specific binding of 125I-PDGF-BB in addition to mRNA expression of the 6-kb transcript for the PDGF beta type receptor. Further evidence for the presence of functional PDGF beta receptors in H-157 cells was obtained from an in vitro kinase assay, which demonstrated a ligand-induced receptor autophosphorylation as well as the phosphorylation of a number of potential substrates associated with the activated receptor.