To confirm our findings in the H4 cells in a more relevant cell model, we investigated the degradative effect of both cathepsins on pathology-associated SNCA in PD patient-derived human iPSC-derived dopaminergic (DA) neurons expressing the SNCA point mutation p.A53T together with the isogenic corrected iPSC line (A53T corr). The gene discussed is CTSS; the disease is Parkinson disease.