EPAS1 and neoplasm: More specifically, it has been observed that hypoxia and enhanced HIF‐1α and HIF‐2α expression and activity, which frequently occur during tumour progression, may result in the upregulation of different stemness gene products that increase tumourigenicity (Heddleston et al., 2009; Ma et al., 2011; Mimeault and Batra, 2013).