ABCG2 and cancer: Several studies have suggested that EMT triggering would confer a stem cell phenotype to cancer cells (cancer stem cells, CSC), with the onset of SP features, such as expression of dedifferentiation markers such as Oct-4 and Nanog, and overexpression of the ABC transporters ABCB1 or ABCG2 [70,71], as reviewed by Mohan and co-workers [72].