The Type I n II TGF-fi Receptor Signals Diverse Responses Cooperation with the Type I Receptor

Transforming growth factor-/3 (TGF-/3) is prototypic of a large family of cytokines conserved from insects through humans. TGF-/3 is multipotential, being able to control cell proliferation, differentiation, adhesion, migration, extracellular matrix production, and other activities (for review, see Lyons and Moses 1990; Mas-sagu6 1990; Roberts and Sporn 1990). Regulation of these functions is important in tissue development and repair processes. The ability of TGF-/3 to inhibit pro-gression through the cell cycle and to control cell com-mitment o terminal differentiation provides unique opportunities to elucidate the molecular events that support hese important processes. TGF-/3 and related cytokines initiate their effects by interacting with mem-brane receptors, ome of which have been molecularl