FABP4 and Other metabolic disease: AFABP, also known as fatty acid–binding protein 4, is an adipokine released preferentially from adipocytes, as well as from macrophages and endothelial cells.15 Fatty acid–binding proteins are a family of cytoplasmic proteins that bind long-chain fatty acids and other hydrophobic ligands.16 The regulation and role of circulating AFABP in metabolic disease have not yet been defined.