The ABC transporter subfamily B member 1 [ABCB1, also known as Multi-Drug Resistance 1 (MDR1)/ P-glycoprotein (P-gp)], ABC transporter subfamily C member 1 [ABCC1, also known as Multidrug Resistance Protein 1 (MRP1)] and ABC transporter subfamily G member 2 [ABCG2, also known as Breast Cancer Resistance Protein (BCRP)/ MitoXantrone Resistance protein (MXR)/ ATP-Binding Cassette of Placenta (ABCP)] appear to promote MDR in cancer cells [1, 2, 7, 12, 14]. Here, ABCG2 is linked to cancer.