The relationships between transforming growth factor-β (TGF-β) and cancer are varied and
complex. The paradigm that is emerging from the experimental evidence accumulated over
the past decade or so is that TGF-β can play two different and opposite roles with respect to
the process of malignant progression. During early stages of carcinogenesis, TGF-β acts
predominantly as a potent tumor suppressor and may mediate the actions of
chemopreventive agents such as retinoids and nonsteroidal anti-estrogens. However, at …