Sphingosine is synthesized from palmitoyl CoA and serine in a condensation required to yield dihydrosphingosine.
Dehydrosphingosine is then reduced by NADPH to dihydrosphingosine (sphinganine), acylated to dihydroceramide finally oxidized by FAD to ceramide. Sphingosine is then solely formed via degradation of sphingolipid in the lysosome.