Fig. 1.

Sphingosine 1-phosphate (S1P) induces arachidonic acid (AA) release in A549 cells. Cells labeled with ³H-AA were stimulated with 500 nM S1P or vehicle for 10 min, and ³H-AA released into the medium was measured at the indicated time (CPM, counts per minute) (A) or presented as fold change compared with the vehicle-treated cells (B). The cells were treated with the indicated concentrations of S1P for 10 min, and AA release was presented as the fold change compared with the vehicle-treated control cells (C). The data represent the means ± SD of 6 samples from a single experiment representative of 3 independent experiments that gave similar results. P < 0.01 across indicated time points (2–120 min) compared with vehicle-treated cells by Student's t-test. The dose response in C was statistically significant by 1-way ANOVA, P < 0.0001.