THE PRESENCE AND ROLE OF TRANSMEMBRANE TRANSFORMING GROWTH-FACTOR-ALPHA IN CULTURES OF RAT-LIVER EPITHELIAL-CELLS

We assessed the presence and the role of membrane TGF-alpha in two rat liver epithelial cell lines, either parental or transfected with c-fo s proto-oncogene. c-fos overexpressing cells had more TGF-alpha-like a ctivity in their membranes. When TGF-alpha was removed by elastase or neutralized, the growth rates of both cell lines were markedly reduced , but to a higher extent for parental cells. If membrane TGF-alpha see med to play a key contribution in normal cell growth, both cell lines were unable to react to the addition of soluble TGF-alpha, showing tha t these two forms of growth factors are not equivalent. (C) 1995 Acade mic Press, Inc.