STAT3 and hepatocellular carcinoma: It physically interacted with EZH2 and STAT3 and acted as a scaffold to increase STAT3 methylation and subsequent phosphorylation induced by EZH2; in turn, activated STAT3 directly bound onto circ-LRIG3 promoter region to enhance circ-LRIG3 transcriptional activity, thus forming a positive regulatory circuit to promote the progression of HCC (Fig. 7).