FIG. 2.

Phosphorylation of GSK-3 by cAMP-PKA does not require activation of the ERK pathway. Neurons were treated as described for Fig. 1A and then pretreated for 30 min in the absence or presence of 10 μM H-89 or 30 μM PD98059 prior to incubation with 10 μM forskolin (FK) for 30 min. Cell lysates were immunoblotted with phosphospecific antibodies against ERK (Thr202 and Tyr204) (top), p90 RSK (Ser381) (middle), and GSK-3α/β (Ser21 and Ser9) (bottom). Results shown are representative of at least three experiments.