Although Smad pathway has been shown to mediate the prometastatic function of TGF-β in the development of metastases of breast cancer (Kang et al, 2005) and melanoma (Javelaud et al, 2007) in mouse model, our results provide the first evidence that blockade of Smad pathway by Smad7 in colon cancer cells increases liver metastasis. This evidence concerns the gene TGFB1 and breast cancer.