More specifically, it has been observed that hypoxia and enhanced expression and activity of HIF-1α and HIF-2α in cancer stem/progenitor cells and their progenies frequently occur during disease progression and metastases and may result in the up-regulation of different stemness gene products and survival signalling elements [6, 14, 48, 50, 90, 94, 99, 102, 104, 105]. This evidence concerns the gene HIF1A and cancer.