ABCB1 and cancer: Among ABC transporter family, three of them, ABCB1 (P-glycoprotein/Pgp), ABCC1 (multidrug resistance protein 1/MRP1) and ABCG2 (breast cancer resistance protein /MXR/BCRP) appear to play an important role in the development of MDR in cancer cells (Wu et al., 2008; Orina et al., 2009).