SPP1 and Parkinson disease: Indeed, in a recent study of human CSF samples, Shi et al. used a targeted approach to develop a biomarker profile capable of distinguishing patients with PD and AD by detecting dysregulated levels of macrophage colony-stimulating factor 1 receptor, osteopontin (SPP1), pro-low-density lipoprotein receptor-related protein 1, ephrin type-A receptor 4, and metalloproteinase inhibitor 1 [190].