AQP1 and meningioma: Five genes that were down-regulated in the meningiomas compared to the control tissue included AQP1 (aquaporin 1), FRZB (Frizzled b), PECAM1 (platelet and endothelial cell adhesion molecule 1), PDGFRL (platelet-derived growth factor receptor-like), and FBLN2 (fibulin 2).