Of the 16 proteins that were identified by MALDI-TOF mass spectrometry, 11 possess metabolic functions (Table 2) including glyceraldehyde-3-phosphate dehydrogenase (GAPDH) - a known neuroprotective drug target [29]–[32] with a link to PD [33] and apoptosis [34]. Here, GAPDH is linked to Parkinson disease.