Fig. 6. Role of calcium in c-Abl-dependent induction of NOX5 by H₂O₂.

(A) K562/NOX5 cells expressing either wild-type or kinase-dead GFP-c-Abl (green fluorescence) were loaded with HE (red fluorescence) and stimulated or not with 100 μM H₂O₂ in the presence or absence of BAPTA (50 μM), or pretreated with imatinib as described in Experimental Procedures. (B) K562/NOX5 cells expressing the kinase-dead GFP-c-Abl (green fluorescence) were loaded with HE and stimulated with ionomycin (100 nM). Confocal images were recorded using a Zeiss microscope as described in Fig. 5. The scale bar indicates a size of 10 μm. (C) Superoxide assays were performed in K562/NOX5 cells and in K562/NOX5 cells expressing either wild-type c-Abl or kinase-dead c-Abl. The cells were all stimulated with ionomycin (100 nM) after a pre-incubation of 10 minutes with or without H₂O₂ in the presence or absence of BAPTA. Superoxide production was expressed as a percent of the value obtained for non-treated cells in the absence of H₂O₂. The data are the means +/− SEM of 3 to 5 independent experiments. Asterisks indicate statistical significance versus control cells without H₂O₂. ** P < 0.01 or ns.