LRRK2 and Parkinson disease: For example, studies have shown that proteins associated with PD, such as α‐synuclein, can induce ER stress and activate the UPR in neuronal cells.[9] The LRRK2 G2019S mutation is one of the most common genetic risk factors for PD, and its role in promoting ER stress in DA neurons has been suggested in several studies.[10] In this study, we investigated the effects of the LRRK2 G2019S mutation on ER stress in induced pluripotent stem cell (iPSC)‐induced DA neurons and mice and identified potential therapeutic targets for PD.