CSCs can be regulated by stemness markers (Oct4, Sox2, KLF4, c-Myc, Nanog, and others), signaling pathways (Hh, Wnt, Notch, TGF/BMP, Hippo, and other pro-survival pathways), extracellular factors (hypoxia, Tumor-associated macrophages, ECM, and vascular niches), and other factors. This evidence concerns the gene KLF4 and neoplasm.