Some recent advances in the chemistry and biology of transforming growth factor-beta

W ITHIN the past two years, there has been an exponential increase in research on transforming growth factor-beta (TGF-beta). ~ In this brief minireview, we cannot provide a detailed survey of this topic (see referenees 56 and 73 for other reviews). Rather, we will summarize some new results, indicative of the importance of this peptide as a multifunetional regulator of cellular activity. The term ~nultifunetional" implies that TGF-beta may either stimulate cell proliferation and growth, or inhibit cell proliferation and growth, or have numerous other actions having little relationship to either of these two processes. We will develop the theme that many of the actions of TGF-beta are related to the response of cells or tissues to stress or injury, and to the repair of resultant damage. However, it is clear that there is no one principal action for TGF-beta; moreover, the almost universal cellular distribution of its receptor encompasses a very broad spectrum of target tissues.