MAPK9/JNK2 is a member of the c‐Jun n‐terminal kinase 1–3 family robustly activated by environmental stresses, including the PD‐related neurotoxins lipopolysaccharides, 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine, and 6‐hydroxydopamine, to mediate neuronal degeneration.44 This evidence concerns the gene MAPK9 and Parkinson disease.