CCL14 and neurodegenerative disease: Despite that some serum proteins, such as albumin and immunoglobulins, contaminate the exosome proteome data from LC–MS/MS in neurodegenerative diseases, we found three cytokines, namely CCL14, CC18, and TNFRSF1A, which were difficult to quantify due to low concentrations in the previous serum proteome studies [136], but were quantified using the MTNs assay.