Fig. 5.

Effect of dnr and Ara-C selection pressure on S1P, C1P, and ceramide levels in HL-60 cells. A: Effect of selection pressure on levels of S1P and dhS1P. The S1P mass in wt cells was 1.77 ± 0.03 pmol/mg protein. B: Total C1P and C16:0-C1P levels. The total C1P mass in wt cells was 32.75 ± 1.35 pmol/mg protein. C: Total ceramides and ceramide molecular species. wt, HL-60/dnr, and HL-60/Ara-C cells were harvested, pelleted by centrifugation, and washed three times in cold PBS. Lipids were extracted as indicated, and MS was conducted as detailed in Materials and Methods. Results are from experiments run in triplicate. Data are expressed as fold changes compared with wt control cells.