In vivo anti-tumor effect of Y-443 in the established MDA-MB-231 mouse lung metastasis model. MDA-MB-231 cells were intravenously injected into nude mice. From day 33, various doses of Y-443 or vehicle were intravenously administered on a weekly basis into the mice. The results are the mean ± S.D. at day 61. *: p < 0.025, versus vehicle group as determined by the one-tailed Shirley-Williams test.