ABCG2 and cancer: The aim of this study is to demonstrate cytotoxic effect and activity of SN38-PEG-PLGA-verapamil nanoparticles on HT29 cancer cells and based on the above, we investigated the change in mRNA expression level of ABCG2 and BAX and BCL2 gene after treatment with SN38-PEG-PLGA-Ver nanoparticles.