PLC inhibition attenuates IGF-II-stimulated S1P production. A, Serum-starved HEK293 cells were stimulated with 10 nm IGF-II for 5 min, after which lipids were extracted and assayed for SPP and S1P by quantitative mass spectrometry. B, Cells were preincubated with 5 μm U73122 for 30 min before stimulation with 10 nm IGF-II for 5 min and determination of S1P. In each panel, data shown represent mean ± sd of three independent experiments; *, P < 0.05 vs. nonstimulated (NS) (panel A) and IGF-II stimulated (panel B).