The B-CPAP cell line was obtained from a human differentiated papillary thyroid carcinoma. Previous studies showed that the cells present thyroid characteristics such as thyroglobulin production, phenotypic alterations such as synthesis of human chorionic gonadotropin hormone (HCG), expression of neuron specific enolase (NSE) and protein S100, and also somatic mutations of p53 and K-rns oncogenes. The present data further characterize this cell line and show an overexpression of transforming growth factor (TGF beta 1) and c-met gene product i.e. the receptor for human growth factor (HGF). The relation between the phenotypic and somatic alterations in the process of malignancy are discussed.