Folate receptor alpha (FRα, FOLR1) is a glycosylphosphatidylinositol (GPI)-anchored cell-surface glycoprotein that mediates the cellular uptake of folate (vitamin B9). It is highly overexpressed in many epithelial cancers, particularly in ovarian cancer (70-80% of cases), as well as in non-small cell lung cancer, breast cancer, and endometrial cancer, while its expression in normal tissues is largely restricted to apical surfaces of polarized epithelia (e.g., kidney proximal tubules, lungs, placenta).