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. Author manuscript; available in PMC: 2014 May 29.
Published in final edited form as: Clin Chem. 2013 Oct 21;60(1):233–242. doi: 10.1373/clinchem.2013.211953

Figure 1. Workflow of peptidomics study on circulating peptide biomarkers.

Figure 1

A. Circulating peptides are produced in the tumor microenviroment and released into the bloodstream. B. The activity of tumor specific peptidase (CPN, for example) in interstitial fluid is evaluated by ex-vivo cleavage assay. C. Nanopore fractionation is used to extract peptides from serum/plasma samples or the reaction solution from the ex-vivo cleavage assay. D. Quantification and sequence identification of peptides are determined by mass spectrometry. E. In-vivo validation and clinical validation are performed by immunohistochemistry, immunoblotting and mass spectrometry.