Wnt signaling also plays a key role in tumor stem cells: activation of Wnt/β-catenin signaling pathway can promote the tumor stem cell characteristics of ovarian cancer cells and esophageal cancer cells [28, 29], possibly through upregulation of tumor stem cell markers Nanog, OCT-4, and SOX2 [30, 31]. This evidence concerns the gene POU5F1 and ovarian cancer.