ABCG2 and neoplasm: For example, microRNA-451 (miR-451), microRNA-326 (miR-326) and microRNA-328 (miR-328) could amplify the drug sensitivity of tumor cells by down-regulating the expression of MDR1, MRP1 and BCRP genes, and consequently inhibiting the expression of P-gp [14], MRP1 and BCRP proteins [15], respectively.