GJB1 and hepatocellular carcinoma: To elucidate the involvement of upregulated and mislocalized Cx32 in HCC progression, two HCC cell lines were used—HepG2 cells, with a high expression level of Cx32 and functional GJs, and SMMC-7721 cells, with a lower expression level of Cx32 and barely functional GJ (Additional file 1: Figures S1 and S2).