Fig. 2. NCAM is required for the regulation of the cellular response to FGF. (A) At 48 hours after transfection either with a control siRNA, or with siNCAM1 or siNCAM3, NIH-3T3 cells were left untreated or were stimulated with 5 or 10 ng/ml FGF2 for 10 minutes. After the treatment, cells were lysed, subjected to SDS-PAGE and immunoblotting for phospho-ERK1/2, followed by stripping and immunoblotting for total ERK1/2 and NCAM. After longer exposure, the activation of ERK1/2 with 5 ng/ml FGF2 became detectable also in control cells (not shown). (B) Cells transfected with either a control siRNA or with siNCAM1 were left untreated or were treated with FGF2 for the indicated time periods. Cell proliferation was assessed as described in the Materials and Methods. ^*P<0.005, relative to untreated control cells.