Sphingosine-1-phosphate (S1P), the structure of which is shown below, is a phospholipid with a wide range of biological activities, notably, involved in cellular signaling.

For example, S1P modulates cellular proliferation, such as of epidermal cells. The bioactivity of S1P is mediated by multiple receptor subtypes. For example, receptors subtypes 1 and 3, (S1P1 and S1P3 respectively) are both expressed in endothelial cells, and play a role in lung and lymphoid endothelial functions. Thus, agonists of receptors, such as agonists of S1P1, could be of value in the treatment of malconditions such as multiple sclerosis, transplant rejection, and adult respiratory distress syndrome. Agonist stimulation of the S1P1 receptor is modulated by receptor degradation. Ligand stimulation induces receptor phosphorylation, internalization, polyubiquination and degradation (Gonzalez-Cabrera, Hla et al. 2007).
Oxadiazoles and oxazoles have been described for use as sphingosine-1-phosphate receptor ligands, see for examples PCT patent application publication numbers WO2006/131336, WO2008/037476 and WO2008/074821.
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