Celastrol prolongs the survival of mice in an in vivo model of an aggressive AML. (A) Survival of mice developing a HoxA9/Meis1-induced AML. Mice were treated with Celastrol (broken line) or left untreated (solid line). (B) Effect of Celastrol on Myb target genes. Quantitative real-time PCR analysis of c-myc and c-kit mRNA expression was performed on bone marrow cells from AML-induced control mice (black bars) or Celastrol-treated mice (gray bars). Expression was normalized against ribosomal 18S RNA. (C) Replating assays of bone marrow cells from AML-induced control and Celastrol-treated mice. Total bone marrow cells from mice untreated (black bars) or Celastrol-treated (gray bars) were grown in methylcellulose without Celastrol at a concentration of 1 × 10⁴ cells/mL. The cells were replated every 10 days at the same concentration. Asterisks indicate statistical significance (**P < .01, ***P < .001, Student t test).