Fig. 6. Ceramide and diacylglycerol levels in FasL-stimulated A20 and A20R cells. After addition of 100 ng/ml FasL, A20 or A20R cells were incubated for the indicated time periods at 37°C. Lipids were extracted and analyzed using the diacylglycerol kinase assay and expressed as a percentage of basal levels. (A) Ceramide (open circles) and diacylglycerol (filled circles) levels 0-8 hours after FasL stimulation are shown in A20 cells. (B) Comparison in A20 and A20R cells of ceramide levels at the time points 3-8 hours following FasL addition. Results shown (means with standard deviation) were either from an individual experiment done in triplicate in which ceramide levels were already visibly elevated after 3 hours (A) or were averaged from two or more independent experiments done in triplicate for each time point.