ABCG2 and acute lymphoblastic leukemia: ABCA2 is the second member of the A subfamily of ABC transporters which may have a role in MDR (14, 15).Our group has recently suggested that ABCA2is related to poor prognosis in childhood ALL (7, 16, 17).The present study is a literature based review article which explains the aforementioned topics, especially the impact of ABCA2 in multidrug resistance of childhood ALL.