STAT3 and breast cancer: In the noninvasive breast cancer epithelial cell lines MCF-7 and ZR-75-1, it was demonstrated that leptin, through the JAK/STAT3–Akt signaling pathway, can downregulate CCN5 (Cyr61, CTGF, -Nov), promoting EMT activation through the reduction of E-cadherin, the overexpression of vimentin and Snail, and the stimulation of cell migration [153].