VAPB and amyotrophic lateral sclerosis: In this regard, characterization of ALS-caustive mutations on the VAPB MSP domain offers an unprecedented opportunity because two signaling networks have been identified to be associated with the VAPB MSP domain; one linked to lipid trafficking/metabolism via binding to the FFAT-containing proteins; and another connected to Eph-ephrin signaling, by acting as a novel ligand for Eph receptors.