GRIN2B and Parkinson disease: However, PD patients were characterized by a significant increase in the synaptic localization of GluN2A but not GluN2B (Figures 3A,C, TIF fraction; GluN2A PD vs. C: *p < 0.05, GluN2B PD vs. C: p > 0.05, two-tailed unpaired Student’s t-test).