In the clinical setting, the differential expression of CAIX in renal cancers has provided a target for radioimmunotherapy, antibody-mediated gene transfer and vaccination strategies (Tso et al, 2001), and phase I/II trial results with iodine-131 labelled murine monoclonal antibodies have been performed with some antitumour activity (Divgi et al, 1998). Here, CA9 is linked to renal carcinoma.