EPAS1 and neoplasm: Although the microbead-induced pro-tumorigenic effects were eliminated by conditional deletion of either HIFα isoform, there appeared to be an overall difference in the effect of the loss of the 2 HIFα isoforms per se on tumor number and coverage, with a greater tumor burden seen in HIF2α KO mice versus WT and possibly in WT versus HIF1α KO mice (Figure 3C,F,G), consistent with previous studies of lung [23] and intestinal tumorigenesis [19].