MAPK8 and Parkinson disease: We have found that Sab mRNA and protein levels are significantly enriched in the hippocampus, substantia nigra, and cerebellum, areas of the brain vulnerable to neurotoxin stimuli.251 Thus, we contend that the elevated Sab concentrations could lead to robust mitochondrial JNK activity contributing to apoptosis and neurodegeneration in disorders such as AD and PD.