HIF1A and neoplasm: Of the three isoforms, HIF-1 is frequently overexpressed in tumor cells (Weidemann and Johnson, 2008; Robinson et al., 2017), with HIF-2 [endothelial PAS domain protein 1 (EPAS1)] strongly expressed by subsets of tumor-associated macrophages (Talks et al., 2000) and HIF-3 expressed in pulmonary alveolar epithelial cells (Li et al., 2006) and in human kidney (Yang et al., 2015).