(a) and (b) Scatter plots for two pairs of peptides from top protein pair APCS (Serum amyloid P-component) and HGFAC (Hepatocyte growth factor activator). The two classes are represented using red and blue, the axes represent the abundance levels of the two peptides and the black line represents the decision boundary. Peptide sequences of APCS in Figure1a and 1b: GYVIIKPLVWV, DNELLVYK, while corresponding sequences for HGFAC: LCNIEPDER and LHKPGVYTR. (c) and (d) Distribution of peptide signal abundance ratios () from two unique peptide pairs originating from proteins APCS and HGFAC. Red and Blue indicate control and IPS progressors respectively.