LRRK2 and Parkinson disease: Mitochondrial stress, induced by escalating doses of valinomycin caused divergent responses to the fibroblast vulnerability profiles observed between patients harboring LRRK2 mutations (G2019S and R1441C) and sporadic PD lines, when compared to healthy subject control lines, as analyzed by a lactate dehydrogenase (LDH) colorimetric assay (Supp.