Folate receptor alpha (FOLR1), a member of the folate receptor family, is a secreted protein that either anchors to membranes via a glycosyl-phosphatidylinositol linkage or exists in a soluble form with high affinity for binding folate and its reduced derivatives into cells and transport 5-methyltetrahydrofolate into cells. Folate is a necessary component of cell metabolism. Overexpression of FOLR1 may confer a growth advantage to tumors by increasing folate uptake and/or may affect cell proliferation via alternative cell signaling pathways. In healthy individuals, FOLR1 expression is often limited to the apical surfaces of epithelium in the lung, kidney and choroid plexus but is overexpressed in a variety of solid tumours such as ovarian cancer, non-small cell lung cancer, breast cancer, kidney cancer and high-grade osteosarcoma.