STAT3 signaling pathway plays an important role in a variety of CSCs, including breast cancer stem cells [36, 37], LCSCs [38, 39], pancreatic cancer stem cells [40], ovarian cancer stem cells [41], and regulates many downstream pluripotent genes-related to CSCs including OCT4, SOX2, and Nanog [42]. This evidence concerns the gene NANOG and ovarian cancer.