Effects of leptin on different glioblastoma cell lines had been previously examined in vitro, and leptin has been found: i) to induce migration and invasion of C6 rat cells linked to the activation of p38MAP kinase and NF-κB pathway, ii) to promote human U87 cells proliferation mainly through Janus-Activated Kinase (JAK)/Signal Transducer and Activator of Transcription 3 (STAT3) signaling pathway and iii) to enhance growth and migration of human LN18 and LN229 cells along with the activation of the PI-3K/Akt and STAT3 pathways [30–32]. The gene discussed is LEP; the disease is glioblastoma.