LRRK2 and Parkinson disease: On the other hand, we have demonstrated that there is a positive correlation between levels of LRRK2 and phosphorylated Rab10 upon IFN-γ stimulation in human monocytes, and that it is this stimulation dependent-response that may be more indicative of a dysfunctional immune trait and therefore of greater potential use for future PD biomarker development.