Significance Phosphoenolpyruvate carboxykinase (PEPCK) has a unique position in cell metabolism by allowing the flexible use of nutrients for anabolic biosynthetic reactions. PEPCK activity has just recently been described in cancer cells. It has been shown to promote cancer cell survival under nutrient deprivation, a typical feature in solid cancers, as well as cancer growth. To decipher the metabolic downstream pathways of PEPCK is critical for a better understanding of cancer cell adaptive responses under low nutrient stress. Here, we show that mitochondrial PEPCK (PEPCK-M) mediates the synthesis of glycerol phosphate from noncarbohydrate precursors, and that PEPCK-M is needed to maintain levels of glycerophospholipids, major constituents of biomembranes, in starved lung cancer cells.