Myelin Basic Protein (MBP) is the most abundant protein component of the myelin membrane in the central nervous system (CNS). Human MBP has 304 amino acids (aa) and shows 71% and 49% aa sequence identity with the mouse and rat orthologs, respectively. Alternative splicing of a single gene, and the optional posttranslational modification of different aa residues, produces a spectrum of isoforms that range in size from 14 kDa to 21.5 kDa. These isoforms exhibit different developmental and cellular expression patterns, and may have different specialized functions. MBP has a role in both the formation and stabilization of the myelin membrane in the CNS. It has also been suggested that MBP is involved in signaling pathways in neural cells and T cells. Research has shown that antibodies against MBP play a role in the development of multiple sclerosis (MS) for a subset of patients. Additionally, elevated levels of MBP in the cerebrospinal fluid is thought to be a sign of myelin breakdown and could serve as a biomarker for several neurodegenerative diseases including MS, traumatic brain injury, and stroke.