ESR1 and breast cancer: Moreover, through STAT3 and PI3K/AKT pathways, LEP can upregulate the expression of key markers of EMT, angiogenesis and metastasis (e.g., E-cadherin, Vimentin, VEGF, PKM2 and ACAT2) [30,36,80,81,82,83], in both ER+ and ER− BC cells (Figure 3).