Spectrogram of synthesized DAK peptide and peptide extracted from patient serum through Qstar mass spectrometry. A to C represent MS profiles of synthetic peptide. D to F represent MS profiles of serum extracted peptide from a patient with fibrosis stage S2 (Sample No. 62). A and D show the ms profile. B and E are a partial enlargement of 520.3 (also 520.6). C and F are MS-MS of 520.3 (also 520.6), partial magnification and MS-MS of 50 ng/μl synthetic DAK peptide.