Fatty acid binding proteins bind to fatty acids and other lipids to function as cytoplasmic lipid chaperones . They participate in the transport of fatty acids and other lipids to various cellular pathways . The predominant fatty acid binding protein found in adipocytes is FABP4, also called adipocyte fatty acid binding protein or aP2. FABP4 is also expressed in macrophages . FABP4 knockout mice fed a high-fat and high-calorie diet become obese but develop neither insulin resistance nor diabetes, suggesting that this protein might be a link between obesity and insulin resistance and diabetes . Mice deficient in both FABP4 and ApoE show protection against atherosclerosis when compared with mice deficient only in ApoE . Mice carrying a FABP4 genetic variant exhibit both reduced FABP4 expression and a reduced potential for developing type 2 diabetes and coronary heart disease. A related study in humans indicated a similar pattern, suggesting that FABP4 may be a potential therapeutic target in the treatment of these disorders .