Figure 4.

Defective desensitization of the mutant S5A-S1P₁. S1p1^WT/WT and S1p1^S5A/S5A mice were treated with 0.5 mg/kg FTY720 or vehicle, and 2 h later thymocytes were isolated. Cells were incubated with the adenylate cyclase activator forskolin (FSK) and the phosphodiesterase inhibitor IBMX in the presence or absence of 10 or 100 nM of the S1P₁-specific agonist AUY954 for 15 min as described in Materials and methods. Intracellular cAMP concentrations were quantified by ELISA (n = 4; **, P < 0.01) and are expressed as picomoles per 10⁶ cells. Error bars represent means ± SE. Data are representative of two experiments performed.