Sphingomyelins are complex membrane lipids composed of phosphorylcholine, sphingosine, and an acylated group, such as a fatty acid. Lysosphingomyelin is a naturally-occurring lipid which is produced by the removal of the acylated group of sphingomyelin by a deacylase. Lysosphingomyelin may, in turn, serve as a substrate for autotaxin, which removes choline to produce sphingosine-1-phosphate. The receptors and signaling pathways that are activated by lyso-sphingosine are diverse and vary between cell types. Lysosphingomyelin occurs naturally in plasma, is a constituent of lipoproteins, and is increased in some diseases, including dermatitis and Niemann-Pick disease.