We crossed these mice with Hif1αf/f (Hif1α knockout [KO]), Hif2αf/f (Hif2α KO), and both Hif1αf/fand Hif2αf/f (Hif1α/Hif2α double KO [DKO]) mice to analyze tumor development in the kidneys (Figure 4A–I). This evidence concerns the gene EPAS1 and neoplasm.