INS and obesity due to melanocortin 4 receptor deficiency: It is interesting to note that CXCL5 seems to be involved in the promotion of obesity by inhibiting insulin signaling and insulin-induced glucose transport in vitro (Chavey et al. 2009) since an experimental study with mice (La Merrill et al. 2009) and observational studies of humans (Fujiyoshi et al. 2006; Warner et al. 2013) suggest that TCDD exposure may promote the development of obesity and diabetes.