During tumor growth, most solid tumors undergo hypoxia, which is responsible for a more aggressive tumor behavior [108,114] and resistance to radio- and chemotherapy because hypoxia promotes the CSC properties associated with EMT, maintains their plasticity, stimulates early EMT by suppressing E-cadherin and induces unfolded protein response (UPR) [61,64,111,114]. The gene discussed is CDH1; the disease is neoplasm.