In nontumor MCF12A mammary epithelial cells and MCF7 breast cancer cells, leptin induces a mesenchymal phenotype, ZEB1 expression, and a “switch” from E-cadherin to N-cadherin, as well as the classic CD24-/CD44+ stem signature, and a larger number of spheres through STAT3 [159]. The gene discussed is STAT3; the disease is breast carcinoma.