A method for the treatment of cancers and/or tumors by administration of a polypeptide having the sequence SEQ ID NO:4 or a polypeptide having an amino acid SEQ ID NO Y which, when aligned with SEQ ID N: 4, has (a) a percentage of identical residues over SEQ ID NO: 4 length of at least 50%, and (b) a percentage of identical residues over a amino acid sequence SEQ ID NO Y length of at least 65% or fragments thereof having at least 20 contiguous amino acids.