In order to establish if this was specific for the G2019S mutation, we also tested a second PD-related mutation in which kinase activity is increased (I2020T), a mutation in the GTPase domain (R1441C), a kinase dead form (LRRK2-G2019S-K1906M), and the normal human form (hLRRK2). Here, LRRK2 is linked to Parkinson disease.