The present invention relates to AUR1 and/or AUR2 polypeptides, nucleic acids encoding such polypeptides, cells, tissues and animals containing such nucleic acids, antibodies to such polypeptides, assays utilizing such polypeptides, and methods relating to all of the foregoing. Methods for treatment, diagnosis, and screening are provided for AUR1 and/or AUR2 related diseases or conditions characterized by an abnormal interaction between a AUR1 and/or AUR2 polypeptide and a AUR1 and/or AUR2 binding partner.