Fig. 3.
Acid-induced DNA damage underlies Dkk1 overexpression. A: phosphorylated histone H2AX (γH2AX) nuclear foci formation in EPC2 cells following chronic acid pulsing. Note increase in γH2AX-containing nuclear foci in acid-treated, but not untreated control, cells. 4′6-Diamidino-2-phenylindole (DAPI) staining demonstrates total number of cell nuclei in the same field. Cells treated with camptothecin served as positive control. Images represent results from 3 experiments. B: quantitative RT-PCR analysis of Dkk1 mRNA expression in EPC2 cells 24 h after treatment with camptothecin (1 μM) or exposure to UV-B radiation (100 J/m2). Values are means ± SE of 3 experiments. **P ≤ 0.001 vs. (untreated) control.