Leptin leads to the proliferation of cancer cells through the activations of the JAK/STAT (Janus kinaze/signal transducer and activator of transcription), MAPK/ERK (mitogen activated protein kinase/extracellular-signal-regulated kinase), PI3K/Akt (phosphatidylinositol 3-kinase/protein kinase B) and suppressor cytokine signaling pathways [42,43]. The gene discussed is SOAT1; the disease is cancer.