<prompt> In AML best prognosis is seen withAcute megakaryocytic leukemiaAcute monocytic leukemiaAcute promyelocytic lukemia M3Erythroleukemia  <response>: - Acute Promyelocytic Leukemia APML: characterized by a gene rearrangement involving retinoic acid receptor It is very responsive to all-trans retinoic acid ATRA, tretinoin combined with anthracyclines and cytarabine. The success of this therapy makes Bone marrow transplantation unnecessary in 1st remission. Arsenic trioxide is also an effective non-cytotoxic therapy for APML 