Fig. 9. ERK1 and ERK2 are activated by CD treatment. The upper panels in (A,B) illustrate MBP phosphorylation by activated ERK1 and ERK2, respectively, as determined by the coupled immunoprecipitation—in-vitro-kinase assay at various times (mins) following CD addition. PD98059 (20 µM) or serum (final concentration of 20%) was added where indicated. Western blotting and Ponceau S staining served to confirm ERK and MBP levels, respectively (middle and bottom panels in A,B), used for normalization of MBP phosphorylation activity. Data plotted are the means±s.d. for at least three different experiments.