In vivo efficacy of oridonin on t(8;21) leukemia. (A) Oridonin prolongs lifespan of C57 mice bearing AEtr-expressing leukemic cells. (B) Oridonin (7.5 mg/kg per day) plus Ara-C (25 mg/kg per day for 5 days, Ara-C-L) further improves survival of the mice. (C) However, oridonin treatment cannot prolong lifespan of FVB/NJ mice bearing PML-RARα–expressing leukemic cells. (D) Oridonin reduces leukemic cell infiltration in C57 mice. (E) TUNEL assay is performed on specimen from C57 mice. The results show that oridonin induces apoptosis of leukemic cells in vivo. (F) Marrow pathological section stained with hematoxylin-eosin (HE) of mice treated with Ara-C and oridonin. (G) Changes in body weight of mice treated with oridonin and Ara-C. (H) Oridonin inhibits tumor growth in nude mice inoculated with Kasumi-1 cells. The numbers in parentheses represent the number of animals used in each group of this study. Error bars in H represent SD. Stainings were analyzed using an Olympus BX51 research microscope equipped with either a 100×/1.30 NA or a 40×/0.75 NA oil objective, and images were processed using Adobe Photoshop CS.