Leptin produced by adipocytes in the mammary/breast tumor microenvironment of obese females may not only act on tumor cells to make them acquire a more aggressive phenotype [30,31], but as we showed here in the in vitro experiments, acting together with other paracrine factors from the tumor microenvironment may also contribute to increasing macrophage recruitment to the tumor. The gene discussed is LEP; the disease is breast neoplasm.