Bombyx mori 3-dehydroecdysone reductase is a founding member of aldo-keto reductase family 2 member E4 (AKR2E4). It is a NADP-dependent oxidoreductase with high 3-dehydroecdysone reductase activity. It may play a role in the regulation of molting and has lower activity with phenylglyoxal and isatin (in vitro). This family also includes 3-dehydroecdysone 3b-reductase from Spodoptera littoralis and Trichoplusia ni, DL-glyceraldehyde reductase from Drosophila melanogaster, aldo-keto reductase from Bombyx mori, which correspond to aldo-keto reductase family 2 member E1, E2, E3 and E5 (AKR2E1/2/3/5), respectively.