 However, CRMP-2 and CRMP-5 are found to be co-expressed in post-mitotic granular neurons.CRMP expression is highest when neurons and synaptic connections mature actively during the first postnatal week, suggesting CRMPs’ role in neuronal migration, differentiation and axonal growth.Indeed, CRMP-2 expression is induced by neuronal differentiation promoting factors such as noggin, chordin, GDNF, and FGF.