MUC1 and hepatocellular carcinoma: The results showed that Smad3 levels in MUC1 knocked down MR1-D4 and MR1-D9 cells were significantly reduced but were increased in MUC1 overexpressing Bel7402 and Hep3B cells compared to the control cells (Figure 2A and 2B), suggesting that MUC1 can affect Smad3 signaling in HCC cells.