Expression of Ki-67 in the kidney. Immunofluorescent labeling of Ki-67 in sham-operated and Nx rats at 1, 2, 4, and 8 wk after surgery is shown. Red signals for Ki-67 merged with green signals for phalloidin and with blue signals for 4′,6-diamidino-2-phenylindole (DAPI). *, Glomeruli. Scale bars 100 μm. Stained nuclei in the proximal tubules were counted in 3 independent regions at 100-fold magnification. s, Sham-operated rats; 1, 2, 4, and 8, Nx rats at 1, 2, 4, and 8 wk after surgery. Multiple comparisons were performed with Dunnett's 2-tailed test after a 1-way ANOVA. **P < 0.01, significantly different from sham-operated rats.