SCD (stearoyl-CoA desaturase) is an endoplasmic reticulum-localized oxidoreductase that catalyzes the introduction of cis double bonds at the delta-9 position in saturated fatty acyl-CoA substrates 12. It converts palmitoyl-CoA and stearoyl-CoA to monounsaturated fatty acids (16:1 and 18:1) 3, utilizing O2 and electrons from cytochrome b5. Based on limited published evidence, SCD plays important roles in lipid biosynthesis, membrane phospholipid and triglyceride production, and energy homeostasis through regulating lipogenic gene expression.