Disclosed is an in vitro method for promoting regeneration, outgrowth or survival of dopaminergic neurons, said method comprising contacting said dopaminergic neurons with a composition comprising an Sp35 antagonist selected from the group consisting of: (i) a soluble Sp35 polypeptide (ii) an Sp35 antibody or immunospecific fragment thereof (iii) an Sp35 antagonist polynucleotide, (iv) an Sp35 aptamer and (v) a combination of two or more of said Sp35 antagonists, wherein said Sp35 antagonist is capable of inhibiting the binding of Sp35 to EGFR. Also disclosed is of an Sp35 antibody or immunospecific fragment thereof that is capable of inhibiting the binding of Sp35 to EGFR in the preparation of a medicament for treating a disease, disorder or injury in a mammal, wherein the disease, disorder, or injury is selected from the group consisting of Parkinsons disease, multiple system atrophy, striatonigral degeneration, olivopontocerebellar atrophy, Shy-Drager syndrome, motor neuron disease with parkinsonian features, Lewy body dementia, progressive supranuclear palsy, cortical-basal ganglionic degeneration, frontotemporal dementia, Wilson disease, Hallervordern-Spatz disease, Chediak-Hagashi disease, SCA-3 spinocerebellar ataxia, X-linked dystoniaparkinsonism (DYT3), Huntingtons disease (Westphal variant), prion disease, Jacob- Creutzfeldt disease (CJD), vascular parkinsonism, cerebral palsy, repeated head trauma, postencephalitic parkinsonism, neurosyphilis, and schizophrenia.
