Activation of kinase cascades in Ebp1 wild type and knock out MEFs. A. The expression of SOS-1 in logarithmically growing wild type and knock out MEFs was measured by Western blot analysis for SOS-1 and actin as indicated. B. WT and KO MEFs were serum starved for 24 hours and then stimulated with EGF (20 ng/mL) for the indicated times. Cells were lysed and Western blot analysis performed to examine the activation states of MAPK (B) and AKT (C) using phospho specific antibodies directed against each protein. The expression of total MAPK and AKT was also measured as indicated. MAPK blots were analyzed by densitometry using Image-J software. Results presented in Panel B underneath each lane are the ratios of pixel densities of the pMAPK to MAPK bands.