RTN4 and multiple sclerosis: Nogo receptor 1 (NgR1) is a high affinity receptor that binds to myelin-associated inhibitory factors (MAIFs).3 MAIFs can include NogoA, myelin-associated glycoprotein (MAG) and oligodendrocyte myelin glycoprotein (OMgp), which are expressed on the myelin membrane lamellae as well as within mature oligodendrocytes,3-5 have been shown experimentally to block neurite outgrowth.6,7 It has been shown that NogoA can potentiate axonal degeneration in the optic nerves and spinal cords of mice induced to develop experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis.8