ACTIVINS AND ACTIVIN RECEPTORS IN CELL-GROWTH

Activin and inhibin, members of transforming growth factor-beta (TGF b eta) superfamily, have diverse and widespread effects within living or ganisms at many stages during growth and development. From the initial isolation of these growth factors based on their effects of FSH secre tion, the study of these factors, as well as of the activin-binding pr otein follistatin, has progressed from the localization of the express ion of the inhibin alpha subunit, activin beta A and beta B subunits, and activin receptors in the tissues of various organisms to the exami nation of activin and inhibin as autocrine and paracrine agents In cel l proliferation and differentiation, The inhibitory effects on cell gr owth and differentiation that have been observed upon treatment of cel ls with activin suggest that further understanding of the bioactivity of this molecule and its characterization on a molecular level may aid in a more complete understanding of eel growth and differentiation. T his minireview discusses the roles of activin, inhibin, and follistati n in the arenas of cell proliferation, differentiation, and embryogene sis, as well as the roles of these molecules in cancerous cells.