GPC3 and hepatocellular carcinoma: Of the 44 MCT4+/GPC3+ HCC cases, we observed reciprocal, synergistic, reciprocal and synergistic, or irrelevant expression pattern of MCT4 and GPC3, which represented 66% (29 cases), 11% (5), 2% (1), and 21% (9) of the cases, respectively (Additional file 2).