Figure 3.

Phosphorylation by Pim kinases protects Socs-1 from degradation. (A) Phosphorylated form of Socs-1 decays more slowly than unphosphorylated form. The 293T cells were transfected with Xpress-tagged SOCS-1 alone (lanes 1–3) or together with Pim-2 (lanes 4–6). A plasmid carrying the LacZ gene was used as a control. Cycloheximide (100 μg/ml) was added to the media 36 h after transfection to block new protein synthesis. Cells were harvested at 0-, 4.5-, and 9-h time points, and total lysates were analyzed by immunoblot with anti-Xpress antibody. (B) The blot in A was scanned and quantitated by using the software nih image 1.6.2. The results from three independent experiments are plotted such that the protein level at 0-h time point is 100%.