Figure 3.

ATM and Chk silencing blocks genotoxic drug-induced ERK phosphorylation, uric acid production, and MICA/B expression. HeLa cells were transfected with scrambled control siRNA, ATM siRNA, Chk1 siRNA, or Chk2 siRNA. After incubation for 24 hr, the cells were left untreated or treated with 5-FU (10 μM) or gemcitabine (2 μM) for another 24 hr. Cell lysates were prepared and analyzed for TAK1 and ERK phosphorylation by Western blot (a) and uric acid levels by using a uric acid assay kit (b). Relative phosphorylation levels were analyzed by quantifying the density of phosphorylated TAK1 and ERK bands normalized by the density of their corresponding total protein bands with NIH Image-J software and presented as bar graphs. Data are the mean ± SD of three experiments. **p < .01, compared to the untreated control. ^##p < .01; ns, not significant, compared to the corresponding control siRNA-transfected controls. Single-cell suspensions were prepared and analyzed for the levels of MICA/B expression (c) by flow cytometry. Green line, isotype control; Red line, MICA/B. The data represent one of three independent experiments with similar results.