Notably, these hypoxia-dependent, HIF-1α- and HIF-2α-induced genes play important roles in regulating different aspects of tumor biology, such as angiogenesis [7], survival [8], proliferation [9], immune system resistance [10], tumor cell plasticity [11], invasion and metastasis [12], chemo- and radio-resistance [13,14], pH regulation and metabolism [15], and maintenance of cancer stem cells (CSCs) [16]. The gene discussed is HIF1A; the disease is cancer.