SFRP2 and hepatocellular carcinoma: Sun’s group has reported that miR-522 promotes cell proliferation of HCC by targeting DKK1 and SFRP2 and activating Wnt signaling (Zhang H. et al., 2016), whereas other researchers report that DDK1 is overexpressed in HCC cells and tissues, and promotes HCC cell migration and invasion through β-catenin/MMP7 pathway (Chen L. et al., 2013).