S100A9 and Alzheimer disease: Kummer and coauthors [23] observed a significantly increased level of S100A9 (which is denoted also as myeloid-related protein Mrp14 [40]) in the brain lysates and cerebrospinal fluid of AD patients compared to age-matched controls and detected S100A9-positive microglial cells in the vicinity of amyloid plaques—thus all data implicated S100A9 as a neuroinflammatory marker of AD.