Although our lab has focused on development of cancer-specific targeting ligands, the cell surface receptors that we have targeted to date have all resided primarily on the malignant cells (e.g. folate receptor alpha 29, 33, prostate specific membrane antigen 34, 35, cholecystokinin 2 receptor 36, 37, carbonic anhydrase IX 38, 39, neurokinin 1 receptor 40, and luteinizing hormone releasing hormone receptor 41, 42). This evidence concerns the gene CA9 and cancer.