Ankyrin repeat-rich membrane-spanning protein (ARMS) is also known as Kinase D-interacting substrate of 220 kDa (KIDINS220). ARMS Promotes prolonged MAP-kinase signaling by neurotrophins through activation of a Rap1-dependent mechanism. Arms may play an important role in regulating postsynaptic signal transduction through the syntrophin-mediated localization of receptor tyrosine kinases such as EPHA4. ARMS may play a role in neurotrophin- and ephrin-mediated neuronal outgrowth and in axon guidance during neural development and in neuronal regeneration. ARMS has also been shown to modulate stress-induced apoptosis of melanoma cells via regulation of the MEK/ERK signaling pathway [taken from the Universal Protein Resource (UniProt) www.uniprot.org/uniprot/ Q9ULH0].