Fig. 1. Drosophila homologs of sphingolipid metabolism. De novo synthesis of sphingolipids (blue). Sphingolipid degradative pathway (red). Phospholipid salvage pathway (green). NGI, no gene identified; NHI, no homolog identified. Palmitoyl-CoA is placed in parentheses to indicate the possibility that Drosophila serine palmitoyltransferase may use a short-chain fatty acyl-CoA substrate.