The invention provides a new tumor tag, RL5 protein, the polynucleotide
encoding RL5 protein, and the method of producing RL5 protein by
recombinant technology. The invention also discloses the use of RL5
protein and the polynucleotides encoding RL5 protein, e.g., in diagnosing
and treating tumor, as well as the pharmaceutical composition containing
RL5 protein or the antibody against it.