To prove that Smad1 was involved in the B7-H3-induced EMT in the colon cancer cell lines, we used two different Smad1-specific small interfering RNAs with different sequences to inhibit the expression of Smad1, and then analyzed N-Cadherin and Vimentin expression, which indicated that the cells had a mesenchymal phenotype. The gene discussed is SMAD1; the disease is malignant colon neoplasm.