Mean cell number in small intestinal crypt (a), small intestinal villus (b), and midcolonic crypt (c) of BALB/c (♦) and DBA/2 (▪) mice after two injections 24 h apart of 100 mg/kg raltitrexed. Mean cell number in small intestinal crypt (a), small intestinal villus (b), and midcolonic crypt (c) of BALB/c (♦) and DBA/2 (▪) mice after two injections 24 h apart of 100 mg/kg raltitrexed. Error bars represent standard errors, four animals at each time point.∗∗ , significant at P < 0.05 by Student’s t test. D. Mark Pritchard et al. Clin Cancer Res 2000;6:4389-4395 ©2000 by American Association for Cancer Research