APOE and Parkinson disease: Adult (young and aged) OPCs show higher expression than neonatal OPCs of some of the proteins associated with AD, PD, HD, and MS (e.g. TAU (67, 68), APOE (69), CRYAB (70, 71, 72, 73), TPPP (74), and SNCA (75, 76) (Fig. 8B).