Notes: Cholestanone is a cholesterol metabolite that has a keto group in place of the 3-hydroxy group on cholesterol.{48122} It decreases TGF-β-induced Smad2 phosphorylation and TGF-β expression and prevents inhibition of DNA synthesis by TGF-β in Mv1Lu cells when used at a concentration of 50 µg/ml.{48123} Increased fecal excretion of cholestenone is correlated with an increased risk of colorectal cancer. Cholestenone reduces serum cholesterol levels in a variety of animal models but is toxic to rats when administered at doses of 700-1,000 mg/kg per day, inducing hypertrophy in and reducing the activity of the adrenal gland.{48124} It has been used as synthetic intermediate in the synthesis of steroids.{48125}