FIG. 4.

Phosphorylation of CREB is diminished in PKIα knockout skeletal muscle. Western blot analysis of phospho-CREB levels. Vehicle-treated (C) and forskolin-treated (F) skeletal muscle organ cultures were analyzed at the specified time points for both wild-type (WT) and PKIα knockout (KO) mice. (a) Eight minutes after treatment. Basal levels of phospho-CREB shown in control (C) lanes are lower in knockout than in wild-type muscles. In addition, levels of phospho-CREB in the induced (F) muscles are also lower in the knockout than in the wild type. Below is a Western blot for total CREB with the same samples. Note that total CREB content is constant in all lanes. (b) Eighteen minutes after treatment. The levels of phospho-CREB induced by forskolin are almost back to basal levels, and the difference in phospho-CREB levels between wild-type and knockout muscle is magnified.