Figure 1.

TNFα-induced sphingomyelin turnover in HUVEC. (A) HUVEC were labeled with [³H]serine for 48 h and treated with TNFα (100 units/ml), total cellular lipids were extracted, and [³H]sphingomyelin was then resolved by TLC at the desired time point. (B) The unlabeled cells were treated with TNFα as indicated above, and cells were lysed to measure ceramide levels by using the diacylglycerol kinase assay. The results represent mean values ± SD from three independent experiments. ∗, P < 0.01; †, P < 0.001, vs. the basal levels.