Mobilization of triacylglycerols. Triacylglycerols in adipose tissue are converted into free fatty acids in response to hormonal signals. 1. The hormones activate protein kinase A through the cAMP cascade. 2. Protein kinase A phosphorylates perilipin, resulting in the restructuring of the lipid droplet and release of the coactivator of ATGL, thereby activating ATGL. 3. ATGL converts triacylglycerol into diacylglycerol. 4. Hormone-sensitive lipase releases a fatty acid from diacylglycerol, generating monoacylglycerol. 5. Monoacylglycerol lipase completes the mobilization process. Abbreviations: 7TM, seven transmembrane receptor; ATGL, adipose triglyceride lipase; CA, coactivator; HS lipase, hormone-sensitive lipase; MAG lipase, monoacylglycerol lipase; DAG, diacylglycerol; TAG, triacylglycerol.