Fourthly, MPP+/ MPTP treatment activates GSK3β and mediates tau phosphorylation, which is dependent on α-synuclein in Parkinsonism models such as SH-SY5Y co-transfected cells, mesencephalic neurons, transgenic mice overexpressing α-synuclein, and post-mortem striatum of PD patients [372]. The gene discussed is GSK3B; the disease is Parkinson disease.