Fig. 5.

Impact of apoptosis on the subcellular distribution of sphingolipids in U251 cells. Subcellular fractionation is performed from STS-treated cells. Lipid extraction and purification are done on 50 μl from each fraction. Sphingolipid levels are then analyzed by UPLC-MS and compared with control (nontreated cells). Impact of STS-induced apoptosis on subcellular levels of ceramide (total chain length) (A), SM (total chain length) (B), sphingosine (C), sphinganine (D), glucosyl-ceramide (E), and lactosyl-ceramide (F). Results are expressed in picomoles of lipid per milligram of proteins (mean ± SEM; *P < 0.05, **P < 0.01, ***P < 0.0001 vs. nontreated cells).