Figure 1: Therapeutic targets in breast cancer stem cells. Three different strategies have been identified for the eradication of BCSCs. (1) The subpopulation of BCSCs can be reduced by targeting proteins differentially expressed in those cells, such as surface markers, transporters, or enzymes. (2) The expansion of BCSCs in tumors can be limited by inhibiting the pathways that control self-renewal (pictured as a self-pointing arrow), such as Notch, Hedgehog, PTEN, Wnt, NF-κB, or BMI-1. (3) Survival, proliferation, and/ or differentiation of BCSCs can be affected by blocking their interaction with normal cells (pictured on the far right) or extracellular matrix at their primary or metastatic niches.