Ephrin type A receptor 4–dependent (Epha4-dependent) axon guidance in development has been extensively investigated; however, its importance is under intense investigation in neurological disorders, including traumatic brain injury (TBI) (13, 14), Alzheimer’s disease (15), amyotrophic lateral sclerosis (16), and ischemia (17). This evidence concerns the gene EPHA4 and early-onset autosomal dominant Alzheimer disease.