It is interesting to note that these two proteins have a 52% amino acid similarity and their superimposed structures are shown in Figure 1A. FABP4 and FABP5 can not only improve insulin sensitivity and the development of atherosclerosis, but also produce significant influences on certain aspects of metabolic diseases, such as diabetes and obesity [17,18,19,20,21,22]. This evidence concerns the gene FABP4 and obesity due to melanocortin 4 receptor deficiency.