Figure 4. Knockdown of catalase enhances As₂O₃-induced apoptosis.

(A, B) ShRNA against catalase or non-specific shRNA was stably transfected into K562 cells (NC for K562^NC, S1 for K562^S1, S2 for K562^S2), the indicated proteins were determined by western blot (A). Thereafter, the cells were treated with As₂O₃ for 24 and 48 h, and the cell viability was determined by annexin V/PI staining (B). (C, D) The indicated cells were treated with As₂O₃ in the presence or absence of DTT (0.2 mM), then the level of ROS (12 h) was determined by FACS (C) and the cell viability (24 h) was determined by annexin V/PI staining (D). All values represent means with bar as S.D. of three independent experiments. (*p<0.05, #p<0.05).