Fig. 7.

Protein phosphatases and NMDA receptor-dependent dephosphorylation of CREB. A, NMDA receptor-dependent dephosphorylation of CREB is blocked by okadaic acid (2 μm), but not by cyclosporin A (250 μm), FK506 (1 μm), or okadaic acid (20nm). Hippocampal cultures (14 DIV) were treated with KCl or forskolin and then with NMDA +/−- phosphatase inhibitors, as indicated. Stimulation protocol, immunoblotting results, and histogram quantification are as in Figure 4. B, Immunoblot of hippocampal neuron cultures at 3, 7, 10, and 15 DIV for PP-1 levels (tubulin used as internal control).