PRIMA-1^Met synergized with BSO in vivo. (A) PRIMA-1^Met and PRIMA-1^Met+BSO treatment inhibited in vivo tumor growth. Seven-week-old female SCID-beige mice were subcutaneously injected with 10 × 10⁶ JJN3 cells. After 6 days, 20 mice bearing similar tumor loads were selected and randomly divided into 4 groups receiving no treatment (control), 18 mg/kg PRIMA-1^MET (intravenous injection), 10 mM BSO (drinking water), or 18 mg/kg PRIMA-1^MET and 10 mM BSO. Treatment was performed daily for 4 days, stopped, and then resumed for 4 additional days. Mice were killed the day after the final treatment (day 15). The tumor volume was assessed at days 6, 9, 13, and 16. *P < .05; ***P < .001. (B) PRIMA-1^Met and PRIMA-1^Met+BSO did not significantly alter body weight. The figure represents the body weights assessed at days 5 and 15 for each mouse (1 symbol per mouse). (C-D) PRIMA-1^Met and PRIMA-1^Met + BSO treatment increased caspase 3 activity. Eight mice were subcutaneously injected with 10 × 10⁶ JJN3 cells. After 7 days, mice received no treatment (control), 18 mg/kg PRIMA-1^MET (intravenous injection), 10 mM BSO (drinking water), or 18 mg/kg PRIMA-1^MET and 10 mM BSO over the course of 4 days. Mice were killed 4 hours after the last treatment, and tumors were disrupted with a dounce homogenizer in 0.4% Triton X-100. Expression of proteins was analyzed by western blotting. Expression of procaspase 3 (arbitrary unit) was normalized, using actin expression.