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Cancer is often difficult to achieve early diagnosis, which is, however, a decisive requisite for favorable outcome in cancer treatments. Cancer biomarkers have been sought for several purposes preferably in blood and pinpointing cancer cells-derived aberrant glycoproteins would be a well-grounded approach to cancer biomarker discovery. One of the glycosyltransferases responsible for aberrant glycosylation in cancer is N-acetylglucosaminyltransferase V (GnT-V), which catalyzes an addition of b1,6-N-acetylglucosamine (GlcNAc) to the core N-glycan, and many lines of evidence have demonstrated the role of N-acetylglucosaminyltransferase V (GnT-V) in cancer development. Tissue inhibitor of metalloproteinase-1 (TIMP-1) and protein tyrosine phosphatase kappa (PTPk) were suggested to be involved in cancer malignancy upon aberrantly glycosylation by GnT-V. In addition to GnT-V, several glycosyltransferase co-works to render the altered glycan structures in cancer cells including sialyl Lewis antigen and core-fucosylation, which prompted us to mine serological biomarker candidates in cancer sera. Immunodepleted on an immune-LC column, serological proteins were enriched by carbohydrate beads conjugated with lectins like L-PHA, DSA, E-selectin, AAL, Con-A. The fraction refractive to lectin enrichments was resolved on an SDS-PAGE gel, and fractionated by molecular mass. Both the captured glycoproteins and gel-separated proteins were tryptic-digested for sequence determination in an LTQ-FTICR mass spectrometer. Candidate proteins showing high sensitivity and specificity during the discovery phase were selected and the panel of biomarker candidates is currently under in-depth analyses for validation.