The MDR in cancer is a multifactorial response of numerous independent as well as interdependent cellular pathways [12], wherein the most critical is the activation of efflux transporter (P-glycoprotein (P-gp), a product of the MDR-1 gene), which results in unpredictable therapeutic effects due to the decreased accumulation of drugs inside the cells [13]. This evidence concerns the gene ABCB1 and cancer.