According to the data from the literature, connexins mostly act as tumor suppressors, i.e., Cx32 in malignant tumors of many sites, Cx26 and Cx43 in breast cancer and Cx43 in lung cancer and melanoma, as well as Cx37 and 40 in laryngeal squamous cell cancer [12,14,15,16]. Here, GJA1 is linked to breast cancer.