As far as we know, the ABC transporter-subfamily B member 1 (ABCB1/MDR1/P-glycoprotein, P-gp), subfamily C member-1/2 (ABCC-1/2, MRP-1/2), subfamily G member 2 (ABCG2, BCRP), and lung resistance-related protein (LRP) play a major role in producing MDR in tumor cells. This evidence concerns the gene ABCG2 and neoplasm.