**4.2 Synopsis of metabolic modules used by immune cells**

There are 7 fundamental inter-linked and co-regulated metabolic modules employed by immune cells to meet their energy demands. These include glycolysis, pentose phosphate pathway (PPP), citric acid cycle/Krebs cycle, mitochondrial oxidative phosphorylation (OXPHOS)/electron transport chain, fatty acid synthesis (FAS), fatty acid oxidation (FAO), and amino-acid metabolic pathways.
