The subject invention relates to isolated proteins, particularly monoclonal antibodies, which bind and neutralize RGM A protein. Specifically, these antibodies have the ability to inhibit the binding of RGM A to its receptor and/or coreceptors. These antibodies or portions thereof of the invention are useful for detecting RGM A and for inhibiting RGM A activity, for example in a human suffering from a disorder including but nor limited to multiple sclerosis, mammalian brain trauma, spinal cord injury, stroke, neurodegenerative diseases, and schizophrenia.