DHRS9 and neoplasm: Previous studies demonstrated that DHRS9 is involved in the biosynthesis of all-trans-retinoic acid (atRA), which displays important anti-tumor activity through inhibition of cell proliferation, induction of cell differentiation, and apoptosis and has been used in several cancer therapies including acute promyelocytic leukemia, squamous cell carcinoma, neuroblastoma, and hepatocellular carcinoma [9–13].