Abstract: The invention relates to the surprising discovery that XAGE-1 is translated as two proteins, a 9 kD protein, termed p9, and a 16.3 kD protein, termed p16. The invention further relates to the surprising discovery that XAGE-1 is expressed in a number of important human cancers, specifically: prostate cancer, lung cancer, ovarian cancer, breast cancer, glioblastoma, pancreatic cancer, T cell lymphoma, melanoma, and histocytic lymphoma. The proteins p9 and p16, immunogenic fragments thereof, analogs of these proteins, and nucleic acids encoding these proteins, fragments, or analogs, can be administered to persons with XAGE-1 expressing cancers to raise or augment an immune response to the cancer. The invention further provides nucleic add sequences encoding the proteins, as well as expression vectors, host cells, and antibodies to the proteins. Further, the invention provides immunoconjugates that comprise an antibody to p16 or to p9, and an effector molecule, such as a label, a radioisotope, or a toxin.