Specificity of expression for connexin genes in astrocytic cells, GJA1/Cx43, GJB6/Cx30, and GJB2/Cx26, was used to verify expected cells of origin for the glial tumors, oligodendrogliomas, and glioblastomas [241,245,246] in REMBRANDT patients on anti-seizure drugs. This evidence concerns the gene GJA1 and glioblastoma.