The well-studied ABC proteins, which are overexpressed in cancer cells, include multidrug resistance protein 1 (MDR1, also known as P-glycoprotein (P-gp)), multidrug resistance associated-protein 1 (MRP1) and ABC-family G member 2 (ABCG2, also called BCRP) 60. The gene discussed is ABCB6; the disease is cancer.