CXCL12 levels are increased in most pathological conditions that CXCR7 is overexpressed in, including tumors [112,113], rheumatoid arthritis [34,114,115], stroke [116,117], multiple sclerosis [118], traumatic brain injury [119,120,121] and obesity [48]. This evidence concerns the gene CXCL12 and obesity due to melanocortin 4 receptor deficiency.