Developmental signaling pathways [including Wnt, Sonic Hedgehog (Shh) and Notch] and oncogenic cascades (including transforming growth factor-beta (TGF-β), Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3), phosphatidylinositol 3-kinase/V-Akt murine thymoma viral oncogene/mammalian target of rapamycin (PI3K/AKT/mTOR), Mitogen-activated protein kinase (MAPK) and V-SRC avian sarcoma (Src) have been identified as key players both in CSCs biology maintenance and in cancer therapy resistance (17, 18). Here, STAT3 is linked to cancer.