Figure 1.
Nuclear Cdk5 acts as a cell cycle suppressor independent of its kinase activity. N2a cells were transfected with GFP-NLS, GFP-NES, GFP-Cdk5-NLS, GFP-Cdk5-NES, GFP-KDCdk5-NLS, GFP-KDCdk5-NES, GFP-Cdk5(S159T)-NLS, and GFP-Cdk5(S159T)-NES. BrdU and phospho-histone H3 immunostaining was performed after overnight growth in BrdU-containing medium after serum add back. A, Representative immunostaining of BrdU-labeled cells. The columns represent the three different GFP-labeled Cdk5 constructs used plus GFP alone. For each construct, proteins were directed to the cytoplasm (bottom row), nucleus (middle row), or expressed with no exogenous trafficking signal (WT) (top row). B, The percentage of GFP-positive cells that were labeled with BrdU was quantified for each construct shown in A. C, The M-phase marker, phospho-histone H3 (P-hisH3) was used in place of BrdU as a mitotic marker for a subset of the constructs examined in A. D, The quantification of the findings in C, expressed as the percentage of GFP-positive cells that were labeled with phospho-histone H3. *,**p < 0.05 by ANOVA. Values are mean ± SEM.