SOX2 and cancer: We extracted the total RNA from the DSF/copper-treated K1 and WRO cells and determined the mRNA expression of several cancer stemness genes, including B Lymphoma Mo-MLV Insertion Region 1 Homolog (BMI1), Homeobox Protein NANOG (NANOG), Octamer-Binding Protein 4 (OCT4), and Sex Determining Region Y-Box 2 (SOX2), by using quantitative RT-PCR to understand the molecular mechanisms through which DSF/copper suppresses thyroid CSCs.