GJB2 and neoplasm: Several of them exert their tumor-suppressing activity via enhancing homophilic cell–cell adhesion (MPZL3, FAT4, GJB2, LMO7, NEGR1, PCDH18, CRYAB, and SERPINB1), maintaining epithelial integrity, or modulating the WNT-, TGFBR-, SHH-, and Hippo signaling pathways and retinoic acid metabolism, exerting thereby anti-EMT and anti-metastatic effect.