A polypeptide obtainable by inducement under hypoxic conditions having a sequence comprising: (a) the amino acid sequence of SEQ ID NO:1 or 3 or a fragment thereof; (b) an amino acid sequence encoded by the nucleotide sequence of SEQ ID NO: 2 or 4 or a fragment thereof; or (c) an amino acid sequence resulting from deletion, addition, insertion or substitution of one or more amino acids in the amino acid sequence of SEQ ID NO:1 or 3; a polynucleotide encoding the above polypeptide or the fragment thereof useful for producing the above polypeptide by a biotechnological technique; and an antibody or fragment thereof specifically binding the above polypeptide.