An acquired transmembrane domain SNP, resulting in the change of R482 to threonine or glycine, was identified in several cancer cell lines in vitro. It has received considerable interest, because it was shown to be a gain-of-function mutation leading to increased mitoxantrone and doxorubicin resistance compared to the WT as well as the ability to transport daunorubicin, rhodamine 123 and LysoTracker green, unlike WT ABCG2 (18–20). This evidence concerns the gene ABCG2 and cancer.