Increased levels of Cx43 correlate with TMZ resistance in GBM cells, and GBM patients that present high levels of Cx43 mRNA and low tumor levels of O6-methylguanine-DNA methyltransferase (MGMT), an enzyme that repairs TMZ-induced DNA lesions, have significantly shorter life spans than those with low levels of Cx43 mRNA [25–27]. This evidence concerns the gene GJA1 and glioblastoma.