PDE4B2 controls cAMP effects on caspase-9 and caspase-3 activity and BAD phosphorylation. (A) Caspase-9- and caspase-3-like activity in forskolin-treated parental DHL6 cells. After 40 μM forskolin treatment for the specified time periods, cell lysates were harvested and caspase-9-like (▦) and caspase-3-like (▪) activities were measured against 200 μM of their respective substrates (Ac-LEHD-p-NA and Ac-DEVD-pNA) in the presence or absence of their respective inhibitors (Ac-LEHD-CHO and Ac-DEVD-CHO). (B-C) Caspase-9- and caspase-3-like activity in PDE4B2-WT and PDE4B-PI cells in the presence or absence of forskolin. The cells were incubated with 10 μM forskolin, and caspase-9-like or caspase-3-like activity was determined at 9 and 18 hours, respectively. Data in panels A-C represent the mean and SD of 3 independent experiments. (D) BAD phosphorylation in DHL6-parental or DHL6-PDE4B-WT cells treated with forskolin/rolipram. The indicated cells were incubated with 40 μM forskolin and 10 μM rolipram for the specified time periods; cell lysates were harvested and immunoblotted for pBAD (Ser 136). Equal loading was established by reprobing with antibodies directed against total BAD or total AKT. Co indicates control.