FABP4 (Fatty Acid Binding Protein 4, adipocyte-type fatty acid binding protein) is a small cytoplasmic transport protein of the fatty acid binding protein superfamily, encoded by the FABP4 gene with a molecular weight of approximately 15 kDa. Specifically expressed in adipocytes and macrophages, FABP4 is a hallmark protein of adipose differentiation and lipid metabolism. It primarily mediates the uptake, binding, transport, and storage regulation of long-chain fatty acids, maintaining lipid homeostasis and participating in adipocyte differentiation, tissue remodeling, and lipid signal transduction. FABP4 can be secreted extracellularly to modulate systemic metabolism. Its aberrant overexpression induces lipid accumulation, insulin resistance, inflammatory responses, and vascular endothelial damage, closely correlating with the progression of obesity, hyperlipidemia, atherosclerosis, and metabolic syndrome, and acts as a vital biomarker for lipid metabolic disorders.