Gossypol-mediated superoxide production and effect of caspase inhibitor or antioxidant on superoxide production in CLL lymphocytes. (A) Gossypol increases the production of superoxide in CLL lymphocytes. CLL primary cells were incubated for 24 hours either (i) alone or (ii) with 30 μM gossypol for 24 hours, and the superoxide production was measured by flow cytometry using hydroethydine (HEt). (B) Effect of a caspase inhibitor and an antioxidant on gossypol-induced superoxide production. CLL primary cells were incubated for 24 hours (i) alone, (ii) with Z-VAD.fmk, (iii) with NAC, (iv) with 30 μM gossypol plus Z-VAD.fmk, (v) with 30 μM gossypol plus NAC, or (vi) with 30 μM gossypol, and then the superoxide production was measured.