To further determine the biological role of SMAD7 in liver cancer cells, we investigated the effect of the overexpression of SMAD7-Flag and found that this markedly decreased the cell growth ability compared with that of the control in Bel-7404 and SMMC-7721 cells (Figure 4A, *p=0.0110<0.05, **p=0.0026<0.01). The gene discussed is SMAD7; the disease is liver cancer.