Fig. 3. Modulation of Cdk5-p35 activity regulates phospho-NF levels in neuronal perikarya. Micrographs present representative DRG neurons treated for 2 hours with 100 µM roscovotine or microinjected with Cdk5-p35 (together with fluorescein-conjugated tracer) as indicated. Following a 2 hour incubation, cultures were fixed and processed for immunofluorescence with RT97 without extraction. Axons are indicated by arrows. The corresponding phase-contrast image is also presented for the microinjected neuron to facilitate visualization. The accompanying graph presents the mean (± standard deviation) relative perikaryal fluorescence for 10 to 50 cells. Notice the reduction in perikaryal RT97 immunoreactivity by roscovitine and the increase in RT97 immunoreactivity in cells injected with Cdk5-p35.