PLK2 and Parkinson disease: The purposes of the present study were to clarify the neuroprotective effects of post-treatment of PCA for PD treatment by mitigating mitochondrial dysfunction and oxidative damage, and to further determine whether its effects were mediated by the polo-like kinase 2/phosphorylated glycogen synthase kinase 3 β/nuclear factor erythroid-2-related factor 2 (PLK2/p-GSK3β/Nrf2) pathways.