ZEB1 and cancer: Hypoxic microenvironments lead to upregulation and stabilization of hypoxia‐inducible factors (HIFs), which are known to regulate expression of several genes (for example SNAIL, ZEB1, TWIST, matrix metalloproteinases, lactate dehydrogenase A and pyruvate dehydrogenase kinase 133, 34, 35, 36, 37, 38) that contribute to cancer progression, including many involved in cell survival, angiogenesis, glycolysis, cancer invasion, and metastasis.