ABCG2 and acute lymphoblastic leukemia: To verify the underlying mechanism(s) for poor response of t(17;19)‐ALL to VCR and DNR, we focused on ABC transporters,24, 25 since the IC50s of DNR and VCR that are sensitive to ABC transporters are correlated with each other in t(17;19)‐ALL and t(1;19)‐ALL cell lines.