TKT and glioblastoma: According to the obtained results, it can be concluded that the β2-AR agonist, via the upregulation of Cx43 expression, can increase the permeability of cytotoxic metabolites, such as GCV-TP, to GBM cells and thus, through the enhancement of the bystander effect between the cells, could increase the efficacy of HSV-TK/GCV gene therapy in these tumors.