It would be very exciting to repeat this work with the humanized CD34+ mice and determine whether iv delivery of select human cytokines that were elevated by the MPTP treatment and in human PD plasma, IL-1α, IL-2, IL-4, or IL-6, are sufficient to produce the brain changes observed (i.e. gliosis, motor deficit, loss of TH staining, and elevated brain cytokines). The gene discussed is IL4; the disease is Parkinson disease.