BCL2 and Parkinson disease: Furthermore, in the case of PD, decreased levels of anti-apoptotic Bcl-2, elevated levels of pro-apoptotic proteins including BAX, and overexpression of active caspase-3, -8, and -9 have been detected in dopaminergic neurons in post-mortem and in vitro studies, which is further suggesting the contribution of apoptosis in PD pathogenesis [50,51,52,53,158].