We performed WST-1 and Western blotting assays and found that MUC1 expression, cell viability and Smad3 expression changed consistently in response to MUC1 gene silencing and overexpression in HCC cell lines, suggesting that MUC1 may enhance HCC cell proliferation by mediating Smad3 signaling. This evidence concerns the gene MUC1 and hepatocellular carcinoma.