CASP8 and Parkinson disease: Abnormal levels of apoptotic markers such as anti-apoptotic (Bcl-2/Bcl-xL) and pro-apoptotic proteins (Bax/Bak/Bad), Bcl-2 protein family members, initiator caspases-8 and -9 and the effector caspases-3 and -6 have been observed in experimental models of AD [68] and PD [69,70,71].