Unlike the Hif1α−/− PyMT+ mice, lung metastatic tumor burden in Hif2α−/− PyMT+ mice was not significantly different than Hif2αf/f PyMT+ mice, as measured by lesion number, total lesion area, individual lesion area, or incidence of lung metastases (Fig. 5d–g). The gene discussed is HIF1A; the disease is neoplasm.