Interestingly, in the tumor microenvironment, leptin and its ObR receptor are overexpressed and leptin produced by cancer-associated fibroblasts promotes proliferation and cell migration in non-small-cell lung cancer (NSCLC) cells, conceivably via the PI3K-Akt and MAPK/ERK1/2 signaling pathways in a paracrine manner [185]. The gene discussed is LEP; the disease is cancer.