This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemotherapy, Subject name: Pharmacology
All-trans-retinoic acid is used in treatment of: 
Select and explain. 
A. Acute promyelocytic leukemia, B. A.L.L., C. CML, D. Transient myeloproliferative disorder
A: Acute promyelocytic leukemia
Answer: A: Acute promyelocytic leukemia 
Explanation: Arsenic trioxide (Trisenox) and all-trans retinoic acid (ATRA) are anti-cancer drugs that can be used alone or in combination with chemotherapy for remission induction of a ceain subtype of AML called promyelocytic leukemia. These drugs cause leukemia cells with a specific gene mutation to mature and die, or to stop dividing. REFERENCE: www.mayoclinic.org