HIF1A and neoplasm: Tumours adapt to chronic hypoxia inducing changes in gene expression through the activation of pro-survival and metastatic genes such as nuclear factor kappa beta (NF-κB), Hypoxia-inducible factor-1-alpha (HIF-1-α), PIM-1 oncogene (PIM-1) and endothelin-1 (EDN 1) (Hamdan and Zihlif 2014; Dai et al. 2011).