Fig. 1.

Mean neutral sphingomyelinase activity (top) and acid sphingomyelinase activity levels (bottom) for saline-treated control C2C12 cells (black bars), cytomix-treated cells (red bars), cytomix + GW4869-treated cells (green bars), and cells treated with GW4869 alone (blue bars). Cytomix elicited a significant increase in both neutral and acid sphingomyelinase activity levels (P < 0.001 for both assays; asterisks indicate statistical significance in this and all other figures). GW4869 blocked the cytokine-induced increase in neutral sphingomyelinase activity but had no effect on acid sphingomyelinase activity levels.