TGF-β is a potent growth inhibitor in normal epithelial tissues and for this reason considerable emphasis has been given to the concept that TGF-β is highly protective against cancer, and that genetic or epigenetic loss of TGF-β signalling leads to tumour outgrowth and progression (Derynck et al, 2001; Wakefield and Roberts, 2002). This evidence concerns the gene TGFB1 and cancer.