ABCG2 and acute lymphoblastic leukemia: Possible association of the patient response to therapy with the mRNA expression levels of several ABC transporters including ABCA2, ABCA3, ABCB1/MDR1, MRP1/ABCC1, MRP3/ABCC3, ABCG2/BCRP, and MVP/LRP, has been previously investigated in chALL (including 21 B-ALL and 6 T-ALL).