It must be noted that EMT and cancer stem cells (CSCs) do not represent a fixed state of phenotype, but reflect a dynamic flux of adaptive biological responses of malignant cells to drug treatment, oxidant stress, and metabolite alterations in their microenvironment; a characterized feature of CSCs, namely increased expression of aldehyde dehydrogenase (ALDH) enzymes, is linked to radiation resistance and tumor recurrence [17,18]. The gene discussed is LDHA; the disease is neoplasm.