TM4SF4 and hepatocellular carcinoma: TM4SF4 protein was found to be highly expressed in HCC cell lines (i.e., QGY-7701, SMMC-7721, BEL-7404, BEL-7404, HepG2, Huh-7, and Hep3B), and low expression was found in the normal liver cell line (i.e., QSG-7701, Chang, and L02).