Aldo-keto reductase family 1 member C3 (AKR1C3) aka PGFS is responsible for the reduction of prostaglandin H2 (PGH2) to prostaglandin F2alpha (PGF2a) (Suzuki-Yamamoto et al. 1999, Komoto et al. 2004, Komoto et al. 2006). There is an additional way of achieving this reaction involving the prostamide/prostaglandin F synthase, FAM213B and thioredoxin (TRX).