PLK2 and Parkinson disease: While LY341495 aggravated toxin-induced midbrain dopaminergic neuron degeneration in sub-acute MPTP-induced PD mice, LY354740 could protect dopaminergic cells in MPTP-treated mice, which might be related to the decreased extracellular glutamate concentration and down-regulated expression of p-fyn/NMDA and PLK2/pS129 α-synuclein in SN of MPTP-treated mice.