Introduction

Function
Retinoic/Tretinoin is the acid form of vitamin A and is also known as all-trans retinoic acid or ATRA. It is a drug commonly used to treat acne vulgaris and keratosis pilaris. It is available as a cream or gel It is also used to treat acute promyelocytic leukemia. It is also available as a generic.
Its success in treating acute promyelocytic leukemia was a major breakthrough in the treatment of this type of leukemia.It works in APL because the majority of cases involve a chromosomal translocation of chromosomes 15 and 17, which causes genetic fusion of the retinoic acid receptor gene to the promyelocytic leukemia  gene.
This fusion PML-RAR protein is responsible for preventing immature myeloid cells from differentiating into more mature cells. This block in differentiation is thought to cause leukemia.
ATRA acts on PML-RAR to lift this block, causing the immature promyelocytes to differentiate to normal mature blood cells thus decreasing promyelocytes.
Application