Fig. 5. Calcium concentrations affect the subcellular localization of active ERKs. A. Rat1 cells were stimulated with EGF (50 ng/ml, 15 min) or BAPTA-AM (15 µM), or pretreated with BAPTA-AM prior to EGF stimulation (15 min). B. Rat1 cells were stimulated with EGF (50 ng/ml, 15 min), with ionomycin (1µg/ml, 45 min) or pretreated with ionomycin (30 min) prior to EGF (15 min). Localization of pERK was detected with the appropriate Ab. C. Rat1 cells were stimulated with EGF (50 ng/ml) or with ionomycin (1 µg/ml) for the indicated times. The cells were then harvested and their extracts were subjected to Western blot analysis with the indicated Abs.