While future research will need to elucidate the role, effectors and downstream biology of the many other LRRK2-phosphorylated Rab GTPases as well as the link to PD, the development of tools and technologies such as phospho-specific monoclonal antibodies and sensitive proteomics mass spectrometry assays has aided in interrogating LRRK2 kinase pathway activity in vivo, including in human peripheral blood [70], [71], [72], [73]. Here, LRRK2 is linked to Parkinson disease.