The actions of insulin and serum both prevented transcriptionand destabilized RDH mRNA. The effects differed indegree, and resulted in different levels of mRNA, but did nottotally eliminate RDH mRNA. In both serum-free medium andinsulin-containing serum-free medium, the amounts of RDHmRNA after 24 h remained 2–3-fold higher compared withserum-containing medium, because the initial concentrationswere 2–3-fold higher. Destabilization of RDHmRNAby insulindepended on active PI3K, Akt, and inhibition of FoxO1. Thereduction but not elimination of RDH mRNA by insulin andserum is compatible with the continued presence and biosynthesisof atRA, and a need for RDH to modulate basal gluconeogenesisand/or its other multiple functions, whether related or unrelatedto energy balance, such as regulating proliferation (70).