For breast cancer, we were the first to demonstrated that Cx43 might be an enhancer of metastasis by providing several pieces of preliminary evidence: (i) Cx43 was highly expressed in aggressive breast cancer cells and tissues compared with the non-aggressive cancer cells; (ii) overexpression of Cx43 potentiated migration and invasion of breast cancer cells; and (iii) suppressing Cx43 expression by miR-381 largely inhibited the migration activity of breast cancer cells. Here, GJA1 is linked to breast cancer.