Semaphorin 3A signaling, through the plexin A1/neuropilin 1 (PLXA1/NRP1) receptor complex, is known to disrupt the differentiation and migration of oligodendrocyte precursor cells and mature remyelinating oligodendrocytes. Both semaphorin 3A and plexin A1 are up-regulated in the central nervous system of patients with multiple sclerosis.