Fig. 6.

Dependency of agonist-stimulated CREB phosphorylation on PKC activity in SH-SY5Y cells. The phorbol ester, PDBu (1 μM) causes a time-dependent increase in phospho-CREB immunoreactivity (panel A). Effects of chronic phorbol ester treatment (1 μM PDBu; 24 h treatment) on CREB phosphorylation stimulated by MCh (1 μM; 1 and 5 min; B) or bradykinin (300 nM; 1 and 5 min; C). Cells were also stimulated with forskolin (10 μM)/IBMX (500 μM) for 10 min (Fk). Representative immunoblots for phospho-CREB, total CREB and γ-tubulin are shown beneath each histogram. Data, normalized to the forskolin/IBMX response (=100%) in the absence of PDBu treatment, are shown as means ± S.E.M. for at least 3 independent experiments. Statistically significant changes caused by chronic PDBu treatment are indicated as ^**p < 0.01.