ABCG1 and ABCG2 are ATP-bindingcassette (ABC) transporter proteins responsible for pumping chemotherapeuticdrugs out of cancer cells, thereby contributing to chemotherapy resistance. ABCG2 reduces the concentration and efficacyof chemotherapeutic agents, such as mitoxantrone and doxorubicin,by scavenging them from the cell. This evidence concerns the gene ABCG2 and cancer.