PCNA and lip and oral cavity carcinoma: A high dietary ω-6/ω-3 ratio (15:1) increased tumour burden of oral carcinoma induced by 9,10-dimethyl-1,2-benz[a]-anthracene (DMBA) and betel quid extract in hamsters, with increased expressions of NF-κB, proliferating cell nuclear antigen (PCNA) and cyclin D1 in a buccal pouch in comparison with a normal (6:1) and low (2:1) ω-6/ω-3 ratio [216].