Our gene expression data reveals that the factors known to regulate the EMT transcription factors such as TWIST1, SOX9, SNAI1, and SNAI2, and mesenchymal markers such as Vimentin and N-cadherin, were all found to be significantly highly expressed in Hi-BCSC tumors as compared to Lo-BCSC tumors, which suggests the significant role played by EMT induction in the expansion of CSCs in the breast cancer. The gene discussed is TWIST1; the disease is breast cancer.