A peptide comprising the amino acid sequence RMFPNAPYL (SEQ ID NO:1) or a portion or variant thereof provided that the peptide is not intact human WT-1 polypeptide or a peptide comprising the amino acid sequence CMTWNQMNL (SEQ ID NO:2) or a portion or variant thereof provided that the peptide is not intact human WT-1 polypeptide or a peptide comprising the amino acid sequence HLMPFPGPLL (SEQ ID NO:3) or a portion or variant thereof provided that the peptide is not intact human gata-1 polypeptide, and polynucleotides encoding these peptides. The peptides and polynucleotides are useful as cancer vaccines.