A. Caspase 3 activity measured in WEHI7.2 (24 h), Hb12 (18 h) and 200R (30 h) cells treated with vehicle, ATN-224, 50 μM paraquat (PQ) or a combination of ATN-224 and paraquat. B. Cell viability in WEHI7.2 and WEHI7.2 variant cells treated with vehicle, ATN-224 (3 nM WEHI7.2; 4.5 nM Hb12 and 200R), doxorubicin (5 nM and 10 nM WEHI7.2 and 200R; 10 nM and 20 nM Hb12) or a combination of ATN-224 and doxorubicin. All values are mean + SEM (n ≥). *, significantly different from vehicle treated control cells (p ≤ 0.05). **, significantly different from ATN-224 treated cells (p ≤ 0.05).