Chemopreventive activity of 6CEPN in a HT29 colon cancer xenograft model. A, effect of 6CEPN on tumor growth. B, effect of 6CEPN on tumor mass. C, effect of continuous 6CEPN treatment on the ratio of TXB2 to 6-keto-PGF1α. D, effect of 6CEPN on body weight of mice. Chemopreventive activity of 6CEPN was evaluated in a 28-day colon cancer xenograft model. Before cell injection, mice were pretreated with 6CEPN for 14 days. 6CEPN dissolved in 5% (v/v) dimethyl sulfoxide (DMSO)/PEG400 was given to the mice by gavage every other day for a total of 42 days. Data are presented as means ± S.E.M. (n = 12 mice). The asterisks indicate a significant (*, p < 0.05; ***, p < 0.001) difference compared to vehicle control group.