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. 2007 Feb;18(2):404–413. doi: 10.1091/mbc.E06-09-0851

Figure 1.

Figure 1.

Inhibition of Cdk5 activity induced sustained Erk1/2 activation in primary cortical neurons. E18 rat embryonic cortical neurons were cultured for 7 d in B27/neurobasal medium and then treated with 50 ng/ml NGF or 20 μM roscovitine, or both and lysates prepared for analysis over a 12-h period. (A) Kinetics of Erk1/2 activation after NGF treatment. Peak Erk1/2 phosphorylation is seen at 15 min followed by a decline to baseline at 3–12 h. (B) Cdk5 immunoprecipitates of lysates (J-3 antibody) during the above-mentioned NGF activation show that the expressions of Cdk5, p35, and Cdk5 activity are constant. (C) Time course of Erk1/2 activation after treatment with roscovitine. An initial peak of activity is reached at 30 min and sustained at that level for 12 h. (D) Combined treatment, pretreated with roscovitine for 30 min and then NGF is added. Erk1/2 activation was sustained up to 12 h at a higher level than roscovitine alone. (E) Line graph shows the corresponding quantification of Erk1/2 phosphorylation in the three different treatment groups. Data represent mean ± SEM of three experiments.