Glypican-3 (GPC3), a member of the glypican family of glycosyl phosphatidylinositol-anchored cell-surface heparin sulfate proteoglycans, plays an important role in cell growth and differentiation (1). Using the 1G12 monoclonal antibody, GPC3 has been identified as a useful tumor marker for the diagnosis of Hepatocellular Carcinoma (HCC), hepatoblastoma, melanoma, testicular germ cell tumors, and Wilms’ tumor. GPC3 protein has been shown to be expressed in most hepatocellular carcinomas (HCC), but not in normal liver nor benign hepatic lesions, including dysplastic and cirrhotic nodules (1-4). Most patients with HCC have significantly elevated serum protein levels of GPC3 (3). Several studies report that GPC3 is a sensitive diagnostic marker for HCC and a tool for differentiating HCC from non-neoplastic and pre-neoplastic liver disease (3,4). In-house TMA-based studies have shown that GPC3 is positive in 90.4% (66/73) of hepatocellular carcinoma cases, and negative in 100% of cholangiocellular carcinoma, normal liver and hyperplasia cases.