Figure 4.

TNP-470-induced G₁ arrest and p21^CIP/WAF accumulation are not observed in primary fibroblast cells. (A) Dose-response curves of BAE cells, MEFs, and murine adult lung fibroblast cells isolated from wild-type (wt), p53^−/−, and p21^{CIP/WAF−/−} mice treated with TNP-470 were compared by [³H]thymidine incorporation assay. (B) Western blot analysis of murine fibroblasts and endothelial (Endo) cells treated with 10 nM TNP-470 for 12 h. Cell lysate (40 μg) from adult lung fibroblasts and MPE cells from wild-type, p53^−/−, and p21^{CIP/WAF−/−} mice was loaded in each well. The protein blot was incubated with anti-p21^CIP/WAF antisera, and immunoreactive protein was detected by chemiluminescence (Upper). The blot was stripped subsequently and reprobed with anti-actin antisera (Lower) as a control for protein loading.