The effect of hydrocortisone (HC) on PDGF beta-receptor expression was studied in the human malignant mesothelioma cell line Mero-14. HC was found to induce a time- and dose-dependent increase of PDGF beta-receptor mRNA. Nuclear run off analysis revealed that HC induced increased transcription of the PDGF beta-receptor gene. The expression of PDGF beta-receptor protein was also elevated by HC as demonstrated with an immunoblotting assay. However, the number of PDGF-BB binding sites on the cell surface of Mero-14 remained unchanged upon HC treatment. These results suggest that steroid hormones can regulate PDGF receptor expression in vivo.