2-Oxoglutarate receptor 1 (OXGR1), also known as cysteinyl leukotriene receptor E (CysLTE) and GPR99, is a protein that in humans is encoded by the OXGR1 (also termed GPR99) gene. The Gene has recently been nominated as a receptor not only for 2-oxogluterate (see alpha-Ketoglutaric acid) but also for the three cysteinyl leukotrienes (CysLTs), particularly leukotriene E4 (LTE4) and to far lesser extents LTC4 and LTE4. Recent studies implicate GPR99 as a cellular receptor which is activated by LTE4 thereby causing these cells to contribute to mediating various allergic and hypersensitivity responses. Montelucast is in use to treat various conditions including asthma, exercise-induced bronchoconstriction, allergic rhinitis, primary dysmenorrhoea (i.e. dysmenorrhoea not associated with known causes; see dysmenorrhea#Causes), and urticaria. It has been presumed that this drug's beneficial effects in these diseases is due to its well-known ability to act as a receptor antagonist for the cysteinyl leukotriene receptor 1, i.e. it binds to but does not activate this receptor thereby interfering with LTD4, LTC4, and LTE4 provocative actions by blocking their binding to CysLTR1.