MTOR and breast cancer: Further studies have revealed that UCA1 might regulate multiple signaling pathways, including EZH2/p21, phosphatidylinositol 3′–kinase/protein kinase B (PI3K/Akt), mammalian target of rapamycin (mTOR), and Wnt/β-catenin, to induce tamoxifen resistance in BC cells [182,184,193].