Although earlier work showed that the downregulation or absence of Cx43-mediated intercellular communication is associated with increased malignancy in tumor cells [4,5], it is now clear that Cx43 overexpression in tumor cells promotes invasion [4,6,7], especially in the presence of normal stromal cells such as astrocytes [8,9,10,11]. The gene discussed is GJA1; the disease is neoplasm.