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. 2000 Oct 24;97(23):12840–12845. doi: 10.1073/pnas.220410397

Figure 4.

Figure 4

PKA activation reduces phospho-Thr-75 DARPP-32 even when Cdk5 activity is inhibited. (a) Slices were incubated in the absence or presence of roscovitine (Rosc) (10 μM or 50 μM) for 60 min, followed by the addition of forskolin (FSK) (2 μM) for 5 min. The amounts of phospho-Thr-75 DARPP-32 were quantified by densitometry, and the data were normalized to the values obtained with untreated slices. Data represent means ± SEM for 4–15 experiments. **, P < 0.01 compared with no addition; †, P < 0.05, ††, P < 0.01 compared with forskolin alone; §§, P < 0.01 compared with roscovitine (10 μM) alone; ¶, P < 0.05 compared with roscovitine (50 μM) alone, Student's t test. (b) Homogenates of neostriatal slices treated with forskolin at the indicated concentrations were subjected to immunoprecipitation (IP) with either a Cdk5 antibody (C-8) or a normal rabbit IgG. The immunoprecipitates, containing Cdk5 and its cofactor p35, were used to phosphorylate histone H1 in the absence or presence of roscovitine. Results similar to those shown here were obtained in two other experiments.