Although there has been accumulating evidence supporting a potential role of FABP4, produced by fat tissues and/or macrophages, in mediating obesity-related cancer development and progression, further studies are needed to elucidate the detailed molecular mechanisms by which cytoplasmic and circulating FABP4 expression interfere with different signaling pathways. This evidence concerns the gene FABP4 and obesity due to melanocortin 4 receptor deficiency.