Fig. 4.

Diminished efficacy of FTY720-P on I45T and G305C mutants. CHO-K1 cells were transduced with lentivirus vectors for the expression of GFP-tagged S1P₁, I45T, and G305C, starved overnight, and then stimulated with 10 nM FTY720-P for the indicated time (A) or for 1 h (B). A: Total cell lysates were prepared and subjected to Western blot analyses for the degradation of S1P₁. B: Cell-surface proteins were biotinylated, purified, and subjected to Western blot analyses to check the amount of S1P₁ remaining on the cell surface after FTY720-P treatment. C: Densitometric analysis of (B) using the National Institutes of Health ImageJ program is shown. Data represent the mean ± SD (n = 3).