CNP and multiple sclerosis: 2′,3′‐Cyclic nucleotide 3′‐phosphodiesterase (CNP) is highly enriched in myelin but is also present in the cell bodies of oligodendrocytes and neurons.38, 39 Data from CNP transgenic and knockout mice suggest important roles for CNP in myelin formation and axonal integrity.40, 41 CNP proteolysis is increased in aged monkeys, resulting in axonal loss during CNS aging.42, 43 Decreased CNP levels are observed in AD and multiple sclerosis, suggesting CNP loss may contribute to neurological diseases.44