STAT3 and cancer: All those external inducers of EMT activate intracellular Hedgehog, Wnt, and Notch signaling pathways along with Cripto-1-mediated signaling, and also transcription-regulating factors HIF1α, HIF2α, signal transducer and activator of transcription 3 (STAT3), NANOG, OCT4, heat shock factor 1 (HSF1), and nuclear factor κB (NFκB) that contribute to cancer cell stemness development and the formation of the CSC niche [1,2,3,4,5,7,8,17].