It is an object of the present invention to provide diagnostic reagents, pharmaceuticals and the like for particular diseases, and providing means that are useful in developing such reagents, pharmaceuticals and the like. The present invention provides a novel polypeptide and a specific partial peptide thereof, as well as a novel polynucleotide and a specific partial nucleotide thereof, that can be used as cancer-specific biomarkers; an expression vector for such a polynucleotide and a specific partial peptide thereof; a transformant incorporating such an expression vector; an antisense molecule, RNAi-inducing nucleic acid (e.g., siRNA), aptamer, or antibody for a cancer-specific biomarker, and a composition comprising the same; a mammalian cell or non-human mammal wherein the expression or a function of a cancer-specific biomarker is regulated; a measuring means (e.g., primer set, nucleic acid probe, antibody, aptamer) for a cancer-specific biomarker, and a reagent comprising them and the like.