PTGS2 and glioblastoma: The first group comprised CXCR4, SPP1, ACKR3, CCL2, PTGS2, CD274 [PD-L1), CXCL11 and suggests that the core region of GBM is characterized by signaling pathways strictly related to hypoxia and strongly favoring stemness and immune tolerance through PD-L1 overexpression.