From these data we found that our predicted EPAS1 downstream target genes significantly overlapped with HIF regulated genes only in primary human pulmonary artery endothelial cells (Fisher's exact test p-value = 0.004) [63], but not with the other hypoxia signatures defined in other tissues such as breast cancer, head and neck cancer, and normal kidney (p-values = 0.74, 0.24, and 0.15, respectively). This evidence concerns the gene EPAS1 and head and neck cancer.