An excess of unlabeled monoclonal anti-CAIX antibody efficientlyinhibited tumor uptake of [111In]In-DTPA-B9, while onlya partial reduction of [111In]In-DTPA-B9-ABDlow and [111In]In-DTPA-B9-ABDhigh uptake was found.Immunohistochemistry and autoradiography images showed colocalizationof all B9-variants with CAIX expression; however, [111In]In-DTPA-B9-ABDlow and [111In]In-DTPA-B9-ABDhigh alsoaccumulated in non-CAIX expressing regions. The gene discussed is CA9; the disease is neoplasm.