TP53 and Parkinson disease: Clinical research found that dopaminergic neurons were damaged through apoptosis signaling pathways, such as p53 (Tatton, 2000; Hartmann and Hirsch, 2001; Nair, 2006), in PD patients, and an increase in activated microglia was observed in the basal ganglia of PD patients (Ouchi et al., 2005).