Tumor hypoxia is associated with resistance to radiotherapy and chemotherapy, and HIF-1α is a key hypoxia-inducible transcriptional factor that upon activation, leads to the upregulation of several important hypoxia-responsive genes that regulate apoptosis, glucose metabolism (e.g. carbonic anhydrase (CA)-9), and angiogenesis (e.g. VEGF receptor (VEGFR) and its ligands) [52]. Here, HIF1A is linked to neoplasm.