Metabolism of C5-DMB-Cer and C6-NBD-Cer in normal and ATP-depleted cells over time. Cells were preincubated  in Ham's F-12 with or without energy inhibitors (50 mM 2-deoxy- d-glucose and 5 mM NaN3) for 15 min at 33°C, then incubated  with 1.25 μM C5-DMB-Cer (A) or 5 μM C6-NBD-Cer (B) for 30  min at 4°C. After washing, cell monolayers were further incubated in Nutridoma medium containing 0.34 mg/ml BSA with or  without the inhibitors for the indicated time at 33°C. Lipids extracted from the cells were separated by TLC, and the amounts  of C5-DMB-SM (solid lines in A), C6-NBD-SM (solid lines in B),  and C6-NBD-GlcCer (dotted lines in B) were determined. Formation of C5-DMB-GlcCer was too low to be quantified. Closed  circles, wild-type cells without inhibitors; open circles, wild-type  cells with inhibitors; closed squares, mutant LY-A cells without  inhibitors; open squares, mutant LY-A cells with inhibitors.
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