S100A9 and early-onset autosomal dominant Alzheimer disease: It is interesting to highlight that ARPC4, cathepsin G, cystatins B and D, mucin 5B, PIP, and S100A9 were also characterized in another salivary interactome that was associated with cystatin B. It was previously investigated in salivary samples from healthy subjects and patients affected by Alzheimer’s disease [35].