PTGDS and meningioma: The Kalamarides lab has previously developed several meningioma GEMMs relying on the Adenovirus Cre (AdCre)-mediated deletion of the Nf2 gene in PGDS (Prostaglandin D synthase)-expressing arachnoid cap cells in mice either in a wild-type or Cdkn2a null background (55, 56).