This family includes P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP1 ABCC1 and MRP2 ABCC2), and breast resistance-associated protein (BCRP or ABCG2), all of which have been found to contribute to multidrug resistance in osteosarcoma [277]. The gene discussed is ABCB1; the disease is osteosarcoma.