CCL2 and obesity due to melanocortin 4 receptor deficiency: Additionally, the expression of APN in the normal individual was significantly higher than those in obesity and T2DM groups, the expression levels of TNF-α and MCP-1 in normal group were significantly lower than those in obesity and T2DM groups (Table 4, P < 0.05), and no significant differences of APN, TNF-α, or MCP-1 expression were detected between obesity and T2DM groups (Table 4, P > 0.05).