An anti-GPC1 monoclonal antibody has shown potent antitumor activity in esophageal squamous cell carcinoma [244], whereas a human monoclonal antibody against GPC3, HS20, destroying Wnt3a and GPC3 interaction and subsequent signaling, exhibits elevated antitumor activity in liver cancer [245,246]. Here, GPC1 is linked to esophageal squamous cell carcinoma.