Stem cells are necessary for tissue maintenance within diverse organs. Several signaling pathways (e.g. JAK/STAT, Hedgehog, Wnt, Notch, Smad, PI3K, and NK-κB) have been shown to mediate various stem cell properties, such as self-renewal, cell fate decisions, survival, proliferation, and differentiation. Cancer stem cells are believed to be responsible for tumor initiation, growth, and recurrence. Numerous inhibitors have been developed to specifically target cancer stem cells by suppressing the expression of pluripotency maintaining factors such as Nanog, Oct-4, Sox-2, and c-Myc and transcription of GLI.