Currently no therapies that provide either protection or restoration of neuronal function for adult onset neurodegenerative diseases such as Parkinson's disease exist. Many clinical efforts to provide such benefits by infusion of neurotropic factors have failed. An alternative approach such as viral construct transduction may be used to directly activate the intracellular signaling pathways that mediate neurotrophic effects and induce axon growth. Viral construct transduction of dopaminergic neurons with a constitutively active human form of the p70S6K gene—hp70S6K (CA)—was shown to induce axon regeneration from living dopaminergic cell bodies that had no living axons.