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). Here, ABCB1 is linked to acute lymphoblastic leukemia.