STAT3 and central nervous system cancer: Activated TFAP2A expression in glioma could negatively regulate the expression of O6-methylguanine methyltransferase (MGMT) and programmed death-ligand 1 (PD-L1) by inhibiting interleukin-6 (IL6)/Janus kinase 2 (JAK2)/STAT3 signaling pathways and also suppress the polarization of glioma-infiltrating microglia to M2 type macrophages, which show immunosuppressive characteristics [48].