PML and acute promyelocytic leukemia: All-trans retinoic acid (ATRA) has been proposed as an alternative therapy for acute promyelocytic leukemia (APL), which is a specific subtype of acute myeloid leukemia (AML) (AML, M3) characterized by a chromosomal translocation t (15; 17) involving the promyelocytic leukemia (PML) gene on chromosome 15 and the retinoic acid receptor-alpha (RARa) gene on chromosome 17, Since 1988[8,9], we and others have shown that a high proportion of APL patients achieve complete remission (CR) with ATRA alone[10,11].