FIG. 7.

Calcineurin activity is required for the Ca²⁺-induced acceleration conversion of IPC to MIPC. (A) Cells were preincubated at 26°C for 10 min with or without 100 mM Ca²⁺, shifted to the appropriate temperature for 10 min, labeled with [³H]serine for 20 min, and chased for 60 min. Sphingolipids were extracted after mild alkaline methanolysis and analyzed by TLC as described in the legend to Fig. 3A. (B) Cells were metabolically labeled with [³H]serine for 20 min and chased for the indicated time. Sphingolipids were extracted and analyzed by TLC as described in the legend to Fig. 3A.