Inhibitory Effect of a Combined Treatment of Glycyrrhizin and Caffeine on Tumor Promotion by 12-O-Tetradecanoylphorbol-13-Acetate in Two-Stage Carcinogenesis in Mouse Skin. J. Pharm. Nutr. Sci. 2013;3(3):202-205. doi:10.6000/1927-5951.2013.03.03.4