Glycerolipid/free fatty acid cycle, and pentose phosphate pathway. Glycerolipid metabolism initiated by glycerol-3-phosphate and pentose phosphate pathway originating from glucose-6-phosphate generate signals for activation of insulin exocytosis. ADSS, adenylosuccinate synthase, LPA, lysophosphatidic acid, DAG, diacylglycerol, TG, triglyceride