A study by quantifying the protein levels of Pi-ATAC on TFs NF-kB and HIF1α in mouse mammary tumors and measuring the DNA occupancy of both found that the primary role of HIF1α protein in the tumor microenvironment of tumor hypoxia is through shaping the regulatory groups in parenchymal tumor cells and infiltrating immune cell subpopulations [162]. The gene discussed is HIF1A; the disease is breast cancer.