Once the oncostatic process has begun, some studies have reported that melatonin, at low doses, impairs the proliferation and apoptotic resistance of oral cancer cells by inactivating ROS-dependent Akt signaling, which is involved in the downregulation of cyclin D1, proliferating cell nuclear antigen (PCNA), and Bcl-2 as well as in Bax upregulation [92]. This evidence concerns the gene PCNA and lip and oral cavity carcinoma.