FIG. 1.
7kchol-induced apoptosis depends on p21waf1 and Stat1. (A) Apoptosis in MEF. Subconfluent cells were treated with 7kchol (15 μg/ml) for 18 h, and apoptosis was quantified by staining with acridine orange and ethidium bromide. (B) Apoptosis in mouse fibroblasts. Mouse fibroblasts were treated with 7kchol (15 μg/ml) for 18 h, and apoptotic cells were counted as described above. (C) Quantification of fragmented DNA in p21−/− and Stat1−/− cells. Cells were incubated with 3H-labeled thymidine for 18 h and treated with 15 μg of 7kchol/ml for 18 h, and DNA fragmentation was quantified. (D) Colony-forming efficiency of p21−/− MEF. Cells were treated with 7kchol (10 to 30 μg/ml) for 18 h, and cells were then seeded in equal numbers (1,000 cells/100-mm dish) in 10% FBS and DMEM. Colonies were counted after 15 days. (E) Colony-forming efficiency of Stat1−/− mouse fibroblasts. Cells were treated with 7kchol as described for panel D. A total of 2,000 cells were then seeded per 100-mm dish, and colonies were counted after 15 days. The data in the graphs in panels D and E depict the colonies formed after 7kchol treatment expressed as a percentage of the colonies formed from cells not treated with 7kchol. Shown in panels D and E are the means and standard deviations of data combined from two experiments.