S100A4 and Parkinson disease: It has previously been shown that S100A4 induces neurite outgrowth in dopaminergic neurons42 and protects them from cell death following exposure to 6-hydroxydopamine (6-OHDA), the neurotoxin which reproduces major pathological hallmarks of PD in animals, including selective dopaminergic degeneration, dopamine depletion, oxidative stress, and neurobehavioral deficits43.