DKK1 and hepatocellular carcinoma: To improve the early diagnosis of HCC, many serum markers of HCC have been identified in the past decades, such as Des-γ-carboxy-prothrombin (DCP), AFP lectin-3 fraction (AFP-L3), glypican-3 (GPC3), Golgi protein 73 (GP73), Dickkopf-1 (DKK1) and so on [15, 16].