LRRK2 and Parkinson disease: However, measurements of pS935-LRRK2 in human brain, peripheral blood neutrophils, lymphoblastoid cell lines and peripheral blood mononuclear cells in several studies across multiple laboratories demonstrate that pS935-LRRK2 levels, relative to total LRRK2, are either unchanged or even decreased in LRRK2 PD and iPD cases compared to controls, and sometimes decreased in LRRK2 PD compared to iPD cases [25-27, 62, 65, 88, 92].