ST1926 induces apoptosis and decreases Tax expression in vivo. (A) Western blot analysis for PARP, p53, p21, and GAPDH on spleen-derived leukemic cells from 3 untreated and 5 ST1926-treated mice at 30 mg/kg every other day for 3 weeks. (B) Average of Tax mRNA expression in spleen-derived leukemic cells from a normal mouse, 3 untreated controls, and 5 ST1926-treated mice. **P < .01, ***P < .001. (C) Quantitative PCR analysis of Tax DNA in spleen-derived leukemic cells from 3 untreated controls and 5 ST1926-treated mice. ***P < .001. Results are represented as percentage of untreated controls ± SD.