SMAD3 and hepatocellular carcinoma: Because several studies by Sorrentino et al and Yamashita et al have shown that TGF-β activates JNK by mediating Smad-independent signaling [36, 37] and our previous study showed that MUC1 expression induces TGF-β1 secretion (data not shown) in HCC cells, we sought to investigate whether MUC1-induced TGF-β secretion could activate JNK and mediate Smad3 signaling.