For example, in a pairwise comparison of [124I]I- and [89Zr] ZrIV labeled versions of girentuximab, which is an internalizing mAb specific for carbonic anhydrase 9, both antibody preparations had equivalent in vivo tumor uptake kinetics in a xenograft model of human clear cell renal cell carcinoma but only [89Zr]ZrIV-girentuximab resulted in prolonged tumor retention (Cheal et al. 2014). This evidence concerns the gene CA9 and clear cell renal carcinoma.