Acute promyelocytic leukemia (APL) is caused by a maturation arrest treatable with trans-retinoic acid.

“the problem with Pro Melo blastic leukemia is not that these terrible-looking cells are multiplying too quickly it's that these cells are facing a maturation arrest ... if you give something and in the case of acute promyelocytic leukemia it's a form of vitamin A called trans retinoic acid if you give that to the patient you remove the maturation arrest the abnormal leukemic cells proceed through normal maturation the disease disappears and the patient is better”