Fig. 5. Ca²⁺-dependent nuclear translocation of 6ROX-CaM in HeLa cells. (A) Cells electroporated with 6ROX-CaM and fluo-4 in 2 mM EGTA (t₀) were stimulated (at t₄₃) with 2.1 mM Ca²⁺. t_1/2 f the translocation of 6ROX-CaM into the nucleus was 85 seconds. At t₅₀₀, the concentration of 6ROX-CaM that was associated with nucleoli and was present in the nucleoplasm had increased 3.9-fold and 1.7-fold, respectively. Nuclear translocation of 6ROX-CaM was measured at 0, 100, 200, 300, 400 and 500 seconds (t₀ to t₅₀₀) and the data are shown in (B). Colored boxes indicate areas that have been measured for nuclear translocation of 6ROX-CaM. (B) Time course of the normalized 6ROX-CaM fluorescence (F/F_(O)cytoplasm) in the () nucleolus, () nucleoplasm and (^*) cytoplasm. The arrow indicates the addition of 2.1 mM Ca²⁺.