FIGURE 5.

Isoproterenol-dependent phosphorylation of CREB at Ser-133 in PDE4KO MEFs. MEFs deficient in PDE4A, PDE4B, or PDE4D as well as wild type controls were incubated with 10 μm ISO for the indicated times and then harvested in SDS sample buffer. Equal amounts of cell extract were separated on SDS-PAGE, and Western blot analysis that was performed usingα-phospho-CREB(Ser-133) and α-CREB antibodies to probe the level of CREB phosphorylation and CREB protein expression, respectively. A, shown are representative pCREB blots for experiments performed using the different MEFs. B–D, the graphs depict the quantification of the time course of CREB(Ser-133) phosphorylation in each of the different MEFs. All data represent means ± S.E. of three experiments performed. Statistical significance was determined by two-way ANOVA.