EFNB3, also known as ephrin-B3, is a member of the Ephrin-B family of transmembrane ligands that bind and induce the tyrosine autophosphorylation of Eph receptors. EFNB3 is expressed on oligodendrocytes and neurons in the hippocampus and along the midline of the spinal cord. It’s up-regulated in glioma and promotes tumor cell invasion and migration. This protein acts as the midline barrier that prevents corticospinal tract projections from recrossing when they enter the spinal gray matter.