To clarify the potential role of Thr509 phosphorylation in neuron CRMP1, we examined how the overexpression of the phospho-mimicking CRMP1 mutant Thr509Asp-CRMP1 affected neurite outgrowth in murine neuroblastoma Neuro2a cells, which are commonly used to study neuronal cytoskeletal dynamics (29). The gene discussed is CRMP1; the disease is neuroblastoma.