SIRT4 and hepatocellular carcinoma: SIRT4 mRNA expression was significantly lower in all five HCC cell lines than in the two normal cell lines (p < 0.01 for HepG2 and Huh7; p < 0.001 for HepG2.2.15 and SNU-387; and p < 0.0001 for Hep3B) (Fig. 3A).