Chain length specificity of dihydroceramides and ceramide production from exogenous PAL. C2C12 myotubes were treated with 1.25 mM PAL with or without myriocin for 14 h. Lipid profiles were determined by LC/MS measurements. A: N-acyl chain lengths of dihydroceramides. B: N-acyl chain lengths of ceramides. Data are means (n = 6) ± SEM of four experiments. In all length of dihydroceramides and ceramides as well as totals, CTL versus PAL, P < 0.05; PAL-MY versus PAL, P < 0.05. CTL, control; MY, myriocin; CER, ceramide; DHC, dihydroceramide.