Figure 5.

Proliferation of c-myc-deficient cells by ectopic expression of ATF3. (A) Wild-type and c-myc-deficient cells were infected with AdATF3 or AdLacZ at 25 MOI for 48 h and their proliferation rates were assayed. Relative cell number is shown as mean±s.d. of triplicate assays. (B) Dose-dependent cell proliferation by ATF3 in c-myc-deficient cells. Significant proliferation by ATF3 compared with control, ^*P<0.05. The lower panel shows the ATF3 expression in AdATF3-infected cells. In the left two lanes, the level of ATF3 expression in serum-stimulated wild-type cells is also shown. (C) Upper left panel: Proliferation rates of the c-myc-deficient cell lines A1 and A2 stably expressing ATF3. The relative cell numbers are the mean±s.d. of triplicate assays. Significant cell proliferation in A1 and A2 compared with control, ^*P<0.05. The upper right panel shows the ATF3 expression in A1 and A2 cells. Lower panel: Morphology of wild-type, c-myc-deficient, and A1 cells is shown. Scale bar, 20 μm.