FIG. 3.
Time course of serum-stimulated ERK2 phosphorylation in wild-type and Mek2−/− MEFs. Primary MEFs were serum deprived for 24 h and subsequently stimulated with 20% FBS or 1 ng of EGF/ml for the indicated times (0, 5, 30, 120, 240, and 480 min). (A) Total cell extracts from wild-type and Mek2−/− MEFs were separated by SDS-PAGE to resolve ERK2 and phospho-ERK2 (p-ERK2), which were revealed by immunoblotting by using an antibody directed against ERK2. (B and C) Quantification with a PhosphorImager of the active form of ERK2 (percentage of phospho-ERK2) in wild-type and Mek2−/− MEFs when they were stimulated with 20% FBS (B) or 1 ng of EGF/ml (C). The means and standard deviations of the results from five wild-type and four Mek2−/− MEF cultures are represented.