TGFB1 and neoplasm: There are many studies in different types of human tumour that have shown that altered inhibition of TGF-β1 cell proliferation during malignant transformation is due to down-regulation of the TGF-β1 receptor system (Derynck et al. 2001; Hata et al. 1998; Paterson et al. 2001; Yamada et al. 2001; Edlund et al. 2003; Lee et al. 2001; Pasche, 2001).