ABCG2 and neoplasm: The molecular mechanisms underlying acquisition of chemoresistance coordinated by Notch signaling are believed to involve the induction of the epithelial-mesenchymal transition (EMT), formation of tumor stem cells, upregulated expression of MDR such as the MDR1, MRP1, BCRP, and HIF-1α, and the enhanced production of oncogenic microRNAs (miRNAs) [48–50].