FIGURE 1.

Effect of serum on the phosphorylation of phosducin-like protein (PhLP) with Chinese hamster ovary (CHO) extract. PhLP was phosphorylated as described in Materials and Methods with ³²P-γATP using kinases found in extract from CHO cells that had been serum starved (no serum) or serum stimulated following serum starvation (serum added). Aliquots were taken at various times and the reactions quenched with 4X Laemmli buffer, run on SDS-PAGE, and the radioactive PhLP band quantified using the phosphorimager. Shown is the 10-min time point. Only kinetics is affected, as later time points show a convergence of the amount of phosphorylation. The phosphorylation is normalized to that found in absence of serum stimulation. The error bar represents the standard deviation from four independent experiments.