ACTIVIN-A INHIBITS GROWTH AND HEXAMETHYLENE BISACETAMIDE-INDUCED DIFFERENTIATION IN HUMAN RETINOBLASTOMA Y-79-CELLS

Activin regulates the growth and differentiation of a variety of cells and is a member of the transforming growth factor-beta (TGF-beta) fam ily. Previously, we found that the retinoblastoma cell line Y-79 expre sses both activins and activin receptors, suggesting that activin may have an autocrine function in these cells. In this study, the effects of exogeneous activin A on cultured Y-79 cells were examined. The resu lts demonstrate that activin A inhibits hexamethylene bisacetamide (HM BA)-induced Y-79 cell differentiation in both serum-containing and ser um-free medium. Activin A also inhibits Y-79 cell growth in serum-cont aining medium but not in serum-free medium.