Receptor-type tyrosine-protein phosphatase R is a member of the protein tyrosine phosphatase (PTP) family. PTPs are known to be signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle, and oncogenic transformation. This PTP possesses an extracellular region, a single transmembrane region, and a single intracellular catalytic domains, and thus represents a receptor-type PTP. The similar gene predominately expressed in mouse brain was found to associate with, and thus regulate the activity and cellular localization of MAP kinases. The rat counterpart of this gene was reported to be regulated by the nerve growth factor, which suggested the function of this gene in neuronal growth and differentiation.