Halofuginone inhibited cell proliferation of breast and prostate cancer cells in vitro (data not shown) and reduced tumor growth in mice at the orthotopic site, showing that its effects are not limited to bone; unlike the effects of other TGF-β inhibitors, including SD208 and overexpression of Smad7 in melanoma cells [12, 15]. This evidence concerns the gene SMAD7 and Familial prostate cancer.