NF2 and meningioma: A more developed mouse model was based on the generation of mice in which meningeal NF2 was conditionally inactivated under control of prostglandin D2 synthase (PGDS) gene promoter, a marker specific for arachnoid cells: NF2-inactivated PGDS-positive meningeal progenitor cells elicited the formation of meningiomas, of both meningothelial and fibroblastic origin, in 38% of mice [369].