SMAD1 and colonic neoplasm: To determine whether Smad1 regulates cell migration in colon cancers, Smad1 was depleted or overexpressed in HCT116/Sw1116 cells using Smad1 siRNA/shRNA or PCDNA3.0-Smad1-expressing plasmid, the protein and the mRNA level of Smad1 were examined by western-blot and qRT-PCR assays (Figures 1A, 1D, 2A, 2D, Supplementary Figure 1A-1D).