CCL2 and obesity due to melanocortin 4 receptor deficiency: In contrast to the widely used genetically modified ob/ob or db/db mice that display excessively elevated fasting blood glucose (190 to 400 mg/dL) and plasma insulin levels (20-fold) [31-33], the current model displays obesity, moderately increased insulin and fasting blood glucose, insulin resistance, and increased MCP-1 in the plasma and peritoneal immune cells (Figures 1 and 2).