Examination of MT dynamics in PP4c^−/− MEF cells. (A) Impairment of MT stability at the centrosome after nucleation in PP4c^−/− MEF cells 48 h after infection of PP4c^cko/cko MEF cells with adeno-Cre. Time (given in seconds) after washout of nocodazole is indicated in the top right corners. Arrows indicate Cre-positive cells. (top) β-Tubulin staining after MT regrowth in PP4c^cko/cko MEF cells (DAPI staining only) and PP4c^−/− MEF cells (arrows indicate DAPI and RFP-Cre positive). (bottom) Statistical analysis of the percentage of cells with observable MT array from the centrosome (n = 200 for each time point of each genotype). (B) Statistical analysis of the newly emanated MTs from the centrosome (*, P < 0.001; n = 12 for PP4c^cko/cko MEF cells and n = 20 for PP4c^−/− MEF cells). (C) Statistical analysis of the number of cells with stacked EB1-GFP at the centrosome (*, P < 0.001; one example of three independent experiments; n = 50). (D) Statistical analysis of fluorescence intensity (in arbitrary units) of EB1-GFP at the centrosome is shown (**, P < 0.05; n = 30 for each genotype). (E) Statistical analysis of the number of plus end tips of MTs in the cytoplasm. We calculated the number of EB1-GFP spots per 100 μm² area in the fixed MEF cells (**, P < 0.05; n = 30 for each genotype). Error bars represent SEM. Bars, 20 μm.