LRRK2 and Parkinson disease: Because Rab10 and LRRK2 are predominantly expressed in monocytes, flow cytometry has been employed to measure cell type-specific Rab10 phosphorylation in heterogeneous peripheral blood mononuclear cell (PBMC) samples, with initial studies again suggesting no difference in Rab10 phosphorylation between PD and control monocyte subsets [48].