<p>This patent application discloses and describes proteins found to be differentially expressed between primary tumor breast cancer cells that did not give rise to recurrent breast cancer disease after initial diagnosis and primary breast cancer cells that did give rise to recurrent breast cancer disease after initial diagnosis. These proteins can be used either individually or in specific combinations in diagnostic and prognostic protein assays on various biological samples from breast cancer patients to indicate the likelihood that a breast cancer patient's cancer will recur after initial diagnosis and treatment. Determination of differential expression of these proteins can also be useful for indicating additional therapies to combat the likelihood of recurrent breast cancer. The full length intact proteins can be assayed or peptides derived from these proteins can be assayed as reporters for these proteins. These proteins can also be identified as "companion diagnostic" proteins, wherein the differentially expressed proteins that arc used as diagnostic and prognostic indicators can also be used as targets for therapeutic intervention of breast cancer. Also disclosed and described herein are isotope labeled versions of peptides from the proteins.</p>
