Genealogy, expression, and cellular function of transforming growth factor-beta.

The transforming growth factor-beta (TGF-beta) gene superfamily expresses a large set of structurally and functionally related polypeptides. Three TGF-beta isoforms are regulated by specific genes and have been identified in mammals (TGF-beta1, -beta2, and -beta3). All three-protein isoforms are observed abundantly during development and display overlapping and distinct spatial and temporal patterns of expressions. Each isoform plays a distinct role, the nature of which depends on the cell type, its state of differentiation, and growth conditions, and on the other growth factors present. TGF-beta regulates many of the processes common to both tissue repair and disease, including angiogenesis, chemotoxins, fibroblast proliferation and the controlled synthesis, and degradation of matrix proteins, such as collagen and fibronectin. This review will examine the genealogy and mode of actions of TGF-beta on the cell types involved in inflammation and repair, as well as in carcinoma.