Increased ABCG2 expression has been linked to cancer stem cells. The proximal miRNA response element (MRE) of ABCG2 is located in the 3’-UTR of ABCG2 mRNA in various cancer cell lines. Interestingly, it was found that this putative MRE of ABCG2 was lost in drug resistant cells and, therefore, the drug resistant cancer cells can evade ABCG2 mRNA degradation and protein synthesis repression mediated by miRNAs, leading to over-expression of ABCG2. This evidence concerns the gene ABCG2 and cancer.