GPC3 and hepatocellular carcinoma: SULF2, which is reported to be an unfavorable prognostic factor for patients with HCC, promotes HCC progression by regulating various cell signaling pathways, including the TGFβ1/SMAD (Zheng et al., 2013; Chen et al., 2017), PI3K/ERK (Lai et al., 2010b; Bao et al., 2013), Hedgehog/GLI1 (Zheng et al., 2013), GPC3/Wnt (Lai et al., 2010a), and GPC3/FGF2 signaling pathways (Lai et al., 2008).