 CRMP-2/tubulin complexes are found in the distal part of the axon and modulate microtubule dynamics by controlling the rate of microtubule assembly.CRMP-2 also contributes to the establishment of neuronal polarity by regulating polarized Numb-mediated endocytosis at the axonal growth cones.In both cases, phosphorylation of CRMP-2 at Thr-555 by Rho kinase or at Thr-509, Thr-514 or Ser-518 by GSK-3β inactivates the protein by lowering binding affinity to tubulin and Numb.