Unraveling the Complex Proteome for Biomarker Discovery in Gastrointestinal and Liver Diseases  Kenneth Song, Samir Hanash  Gastroenterology  Volume 131, Issue 5, Pages 1375-1378 (November 2006) DOI: 10.1053/j.gastro.2006.09.025 Copyright © 2006 AGA Institute Terms and Conditions

Figure 1 Biomarker discovery using proteomics. One or multiple steps may be undertaken for both protein processing and protein analysis. For example, a specimen may have the proteins processed by both labeling with a stable isotope and purifying with a column to analyze only cell-surface proteins. Gastroenterology 2006 131, 1375-1378DOI: (10.1053/j.gastro.2006.09.025) Copyright © 2006 AGA Institute Terms and Conditions

Figure 2 Promising proteomic approaches. (A) Protein microarrays coated either with antibodies or proteins. Red circles represent fluorescent tags that can be detected using a scanner, which are represented by white and red spots on the scanned image. (B) Representative mass ion spectra of a peptide. The heavy labeled peptide is from cancer patient serum and the light labeled peptide is from normal patient serum. Ratio is calculated using total ion intensity. (C) Example of fractionation and isotope labeling of proteins in pancreatic cancer versus control serum. Each row represents a single protein and the columns represent protein fractions based on charge state and hydrophobic properties. Each colored spot identifies the presence of a peptide for that protein in that fraction. Red represents up-regulated in cancer, green is down-regulated in cancer, and yellow is no dysregulation compared with control. Gastroenterology 2006 131, 1375-1378DOI: (10.1053/j.gastro.2006.09.025) Copyright © 2006 AGA Institute Terms and Conditions

Figure 3 Guidelines for biomarker development as set forth by EDRN. Gastroenterology 2006 131, 1375-1378DOI: (10.1053/j.gastro.2006.09.025) Copyright © 2006 AGA Institute Terms and Conditions