Functional transcriptomic studies confirmed the upregulation of EMT and mesenchymal markers, downregulation of epithelial markers, as well as acquisition of signatures associated with cancer stemness (CD56, POU5F1, PROCR, and CD49f), thus transforming MCF-7 cells from oestrogen-positive to triple-reduced (ESR1, PGR, and HER2) status. The gene discussed is ESR1; the disease is cancer.