ABCG2 and cancer: Therefore, we measured the relative mRNA levels of 7 ABC transporters ABCB1, ABCC1, ABCC4, ABCC5, ABCC10, ABCC3, and ABCG2 that are most prominently expressed in Colo 320 cells and are relevant in exporting the applied drugs out of these cancer cells, based on CellExpress and UniProt databases, respectively.