Oxaloacetate is a key intermediate in the citric acid cycle, but it is also needed as a precursor for the synthesis of glucose during gluconeogenesis. Oxaloacetate is also fairly chemically unstable and undergoes spontaneous decarboxylation to pyruvate. Although oxaloacetate is not depleted by participation in the citric acid cycle, it can become depleted by other processes, necessitating its replenishment by various synthetic pathways. Use the Metabolic Map to identify enzymes that can replenish oxaloacetate or other citric acid cycle intermediates.