CCR2 and obesity due to melanocortin 4 receptor deficiency: CC-chemokine receptor 2 (CCR2), a receptor for monocyte chemoattractant proteins (MCPs), plays a pivotal role in the entry of innate immune cells into tissue and influences systemic insulin resistance and adipose tissue inflammation associated with obesity in high-fat-fed murine models (Weisberg et al., 2006).