Neutrophil energetics. Glycolysis is regarded as the dominant source of ATP in neutrophils. The relative contributions of glucose oxidation, glutamate oxidation, and β-oxidation of fatty acids to ATP synthesis in the neutrophil are largely unknown and variably important in other cell types. HIF-1α is an important transcriptional regulator of glucose transporters and of the majority of the enzymes in the glycolytic pathway and is thus a major determinant of ATP levels in myeloid cells. HIF-1α has more recently been reported to regulate PPARG, which itself can increase glucose uptake and regulate lipid metabolism in a range of cell types. Substrate availability may also be critical in determining the consequences of HIF-1α or PPARG activation for the energetic and functional status of the neutrophil.