EXPRESSION OF TYPE-ALPHA TRANSFORMING GROWTH-FACTOR TRANSFERRED INTO A431 CELLS WITH RECOMBINANT RETROVIRUS VECTOR

Retroviral vector 1552 carrying the type alpha transforming growth fac tor (alpha TGF) cDNA was used to obtain a human epidermoid carcinoma A 431 cell Line with stable alpha TGF expression. The conditioned mediu m of the A431/1522-4 clone was found to contain an EGF-competing prote in in amounts 3-4-fold greater than those in the initial A431 line. El ectrophoresis, isoelectric focusing, and immunochemical analysis demon strated that the protein was alpha TGF. Isolated alpha TGF, like EGF, completely displaced [I-125]EGF specifically bound with the receptor, and stimulated EGF receptor autophosphorylation.