MAPK3 and Parkinson disease: Additionally, it has been shown that the ERK1/2- and JNK1/2-c-Jun systems are linked with L-DOPA-induced neurotoxicity of dopaminergic neurons in a cellular model of PD [81] and that PI3K/Akt and ERK1/2 signaling pathways are involved in the protection of dopaminergic neurons against MPTP/MPP+-induced neurotoxicity [82].