Another in vivo study reported that melatonin (25 mg/kg) could synergize the chemotherapeutic effect of 5-fluorouracil (one of the most commonly used chemotherapeutic agents to treat colon cancer) in mice with colon cancer, by promoting the activation of the caspase/poly-ADP-ribose polymerase (PARP)-dependent apoptosis pathway, inhibiting PI3K/AKT and NF-κB/iNOS signaling pathways. The gene discussed is NOS2; the disease is malignant colon neoplasm.