Although larger, more stringent time course studies are required, this suggests that PV-1 is induced in large, well-vascularized tumors in mice, which is similar to the human state, where PV-1 is preferentially expressed in high-grade, well-vascularized astrocytomas (GBMs) than grade I/II astrocytomas [6]. This evidence concerns the gene PLVAP and astrocytoma (excluding glioblastoma).