PGE₂ provokes the phosphorylation of CREB in orbital fibroblasts, an effect blocked with H89.

A: Confluent cultures were treated with PGE₂ (1 µM) for different intervals. Cellular proteins were subjected to Western blot analysis of CREB and pCREB. Densitometric analysis of pCREB protein concentrations are expressed as the ratio to total CREB protein as a percent of the value at “0” min. Data are expressed as the mean ± SD of triplicate independent determinations. (* denotes statistical significance between treatment groups). B: H89 (10 µM) inhibits PGE₂-provoked CREB phosphorylation in orbital fibroblasts. The inhibitor was added for 6 hrs, followed by addition of PGE₂ (1 µM) for 15 min. Cellular proteins were subjected to Western blot analysis of pCREB protein using β-actin as a loading control.