FIGURE 2.

Old WT mice and young S193D mice have increased hepatocyte proliferation after CCl₄ treatment. A, examination of DNA replication in hepatocytes by BrdU uptake. B, number of BrdU-positive hepatocytes was counted and presented as percentage of total number of examined hepatocytes. C, examination of mitotic figures in young and old mice after CCl₄ treatment. The number of mitotic figures was calculated as number per >1,000 hepatocytes. D, expression of PCNA and cdc2 was examined using Western blotting assay. E and F, bar graphs show the levels of these proteins as ratios to β-actin. G, examination of DNA replication in hepatocytes by BrdU uptake. Scale bar, 100 μm. H, number of BrdU-positive hepatocytes was calculated as percentage to the total number of hepatocytes. I, mitotic figures were calculated as number per >1,000 examined hepatocytes. J, expression of PCNA and cdc2 was examined using Western blotting. The filter was re-probed with Abs to β-actin. K and L, levels of PCNA and cdc2 were calculated as ratios to β-actin.