A knockout mouse with CXCR4 ablation created using the Cre-lox P system with fatty acid-binding protein 4 (FABP4) Cre mouse was prone to obesity and hyperglycaemia caused by macrophage infiltration into the WAT and hypoactivity of brown adipocytes15. This evidence concerns the gene CXCR4 and obesity due to melanocortin 4 receptor deficiency.