Fig. 5. Depolarization induces Ca²⁺-dependent nuclear translocation of GFP-PYK2 in PC12 cells. (A) PC12 cells transfected with GFP-PYK2 were treated with high [K⁺]_o (High K⁺) or control solution for 3 minutes in the presence or absence of EGTA (5 mM, added 5 minutes before depolarization). GFP-PYK2 fluorescence and nuclear staining with DAPI were analyzed by fluorescence microscopy. Bars, 10 µm. (B) Confocal sections showing the nuclear localization of PYK2. Bars, 10 µm. (C) Quantification of the percentage of cells with nuclear GFP-PYK2 (i.e. fluorescence in the nucleus that was stronger than or equal to that in the cytoplasm). Values are means ± s.e.m. (three to four coverslips per group). Two-way ANOVA: interaction between depolarization and EGTA treatment F_(1,11)=10.2, P<0.01, depolarization effect F_(1,11)=16.2, P<0.005, EGTA treatment effect F_(1,11)=5.5, P<0.05. Newman-Keuls test: PYK2 control vs K⁺, ^**P<0.01, PYK2 K⁺ vs (PYK2 + EGTA K⁺), °°P<0.01.