In the early stages of liver damage in mice induced by fumarylacetoacetase deficiency, we have shown that SMAD7 can regulate compensatory hepatocyte proliferation by directly inhibiting TGF-β cytostatic effects and apoptosis control.7 Wang et al.5 in comparison reported that SMAD7 acts as tumor suppressor in mice that are constitutively expressing a truncated SMAD7 protein in diethylnitrosamine (DEN)-induced HCC. This evidence concerns the gene SMAD7 and hepatocellular carcinoma.