CCL2 and neoplasm: Elevated plasma leptin concentrations in mice fed a HF diet have been reported previously [39], and the circulating levels of leptin and MCP-1 were elevated in our HF group of tumor-bearing mice, but there was no increase in the plasma TNF-α, perhaps because this proinflammmatory cytokine acts primarily via a paracrine mechanism, as suggested by the finding by Shah et al. [40] that while the plasma levels were unchanged there was an increase in adipose tissue TNF-α mRNA expression in HF-fed mice.