It is derived from myriocin (ISP-1), a metabolite of the fungus "Isaria sinclairii". It is a structural analogue of sphingosine and is phosphorylated by sphingosine kinases in the cell (most importantly sphingosine kinase 2). The molecular biology of phospho-fingolimod is thought to lie in its activity at one of the five sphingosine-1-phosphate receptors, S1PR1. Phospho-fingolimod causes the internalization of S1P receptors, which sequesters lymphocytes in lymph nodes, preventing them from moving to the central nervous system and causing a relapse of multiple sclerosis.