Suppression of T cell proliferation by LysoPS requires GPR174 and Gαs. (a) Sorted naive CD4+ T cells were labeled with CFSE and incubated with plate-bound anti-CD3 and anti-CD28 for three days. On the left, histograms show the proliferation of wild-type (shaded, gray) and Gpr174−/Y (solid line, open) T cells cultured in the presence of the indicated concentration of 18:1 LysoPS. On the right, the division index of the cells is shown. (b) Experiments were carried out as in (A), except with Cd4creGnasfl/fl naive CD4+ T cells; * P < 0.05; ** P < 0.01. Data are representative of three independent experiments. Error bars indicate standard deviation for triplicate measurements.