GJA1 and carcinoma: However, the fact that Cx43 mutations have been found only in invasive structures of exophytic colon adenocarcinoma, but neither among their benign precursors adenomatous polyps nor in endophytic carcinomas, suggests that Cx43 mutational alterations are limited to this specific growth type of human colon neoplasms and are involved at a fairly late stage of their progression [14].