Folate receptor 1 (FOLR1),also known as folate receptor alpha or adult folate-binding protein (FBP),is a 38-kDa glycoprotein belonging to the folate receptor family . The receptor binds to folate and reduced folic acid derivatives and mediates delivery of 5-methyltetrahydrofolate to the interior of cells. FOLR1 is a secreted protein that either anchors to membranes via a glycosyl-phosphatidylinositol linkage or exists in a soluble form. FOLR1 expression is often limited to the apical surfaces of epithelium in the lung,kidney and choroid plexus but is differentially overexpressed in a variety of solid tumors such as ovarian cancer,non-small cell lung cancer,breast cancer,kidney cancer and high-grade osteosarcoma .