FIGURE 1.

CypD regulation of cell proliferation. A and B, LN229 cells stably transfected with non-targeting shRNA (pLKO), CypD-directed shRNA (A), or WT or CypD^−/− MEFs (B) were analyzed for cell proliferation by direct cell counting at the indicated time intervals. Data are mean ± S.D. (n = 3). *, p < 0.05; **, p < 0.01. C, WT MEFs transfected with vector (black), CypD^−/− MEFs expressing control vector (purple), or CypD cDNA (red) were analyzed for cell proliferation by direct cell counting. ***, p < 0.001. D, CypD^−/− MEFs were transfected with vector (pcDNA), WT CypD, or a CypD mutant cDNA lacking peptidyl prolyl isomerase activity (PPI-Mut) and analyzed for cell proliferation by direct cell counting after 96 h. Data are mean ± S.D. (n = 3). *, p < 0.05. E, LN229 cells were transiently transfected with control non-targeting siRNA (Ctrl, left panel) or CypD-directed siRNA (right panel), arrested at the G₁/S boundary by double thymidine block, and analyzed at the indicated time intervals after release for DNA content by propidium iodide staining and flow cytometry. The percentage of cells in the S-phase population is indicated. F and G, quantification of cell cycle transitions in thymidine-synchronized transfected LN229 cells (F) or WT or CypD^−/− MEFs (G) by propidium iodide staining and flow cytometry at the indicated time intervals after release.