With the object of providing a novel protein expression of which is specifically elevated in abnormal cells or abnormal tissue, and also providing a diagnostic method and diagnostic kit for diseases involving elevated expression of a gene encoding that protein, along with a screening method and screening kit for substances for preventing and treating diseases involving elevated expression of a gene encoding that protein, (a) a protein comprising the amino acid sequence represented by Seq. ID No. 2 or (b) a protein comprising the amino acid sequence represented by Seq. ID No. 2 with one or more amino acids deleted replaced or added is provided as a novel protein expression of which is specifically elevated in abnormal cells or abnormal tissue, with a protein expression of which is specifically elevated in abnormal cells or abnormal tissue, the level of expression of a gene encoding that protein is taken as a marker for diagnosing a disease and a reduction effect on the level of expression of a gene encoding that protein is taken as a marker for screening preventative and therapeutic substances for a disease.