Fig. 3. Effects of ERK1 and ERK2 siRNAs on Wnt3a-induced BrdU incorporation. NIH3T3 cells were grown on coverslips in DMEM and either not transfected or transfected with ERK1 or ERK2 siRNAs, or ERK1/ERK2 siRNA for 48 hours. Cells were labeled with 20 µM BrdU 5 hours prior to cytochemical analysis. Where required, 150 ng/ml purified Wnt3a was applied 24 hours before cytochemical analysis. Cell nuclei were stained with DAPI. (A) Quantitative measurement of the percentage of BrdU-positive cells. Analyses were performed at least three times and 100 cells were counted in each case. Error bars indicate the standard deviations of three independent analyses. The right panel shows the western blot analysis of p-ERK1 and p-ERK2 after transfection of NIH3T3 cells with ERK1 and ERK2 siRNA, respectively (B) DAPI, BrdU and merged images of representative non-transfected and ERK1/2 transfected cells after Wnt3a treatment as summarized in A. Bar, 50 µm.