Leptin binds to leptin receptors, activates the MEK/ERK1/2 and PI3K/Akt signaling pathways (33, 34), upregulates the expression of cyclin D1 and anti-apoptotic factor Mcl-1, induces the proliferation and growth of ovarian cancer cells, inhibits apoptosis, and worsens the prognosis of patients with ovarian cancer. The gene discussed is CCND1; the disease is ovarian cancer.