LRRK2 and Parkinson disease: LRRK2 forms dimers at two interfaces: between its WD40 domains and between its COR-B domains (3, 4, 5); these interfaces are important for LRRK2 to form filaments on microtubules, which is enhanced by high expression levels of LRRK2, in the presence of LRRK2 type-I kinase inhibitors, and with overexpression of most PD variants of LRRK2 (3, 6, 7, 8).