Fig. 8. Downregulation of Src kinase activity correlated with increased endogenous APRO4 expression in FGF-stimulated PC12 cells. (A) Upregulation of endogenous APRO4 protein expression in FGF stimulated cells. PC12 cells were serum starved for 20 hours and then stimulated with FGF (25 ng/ml) for the indicated times before being collected. Whole-cell lysates were immunoblotted with the indicated antibodies. Actin was used as internal control to verify equal loading of proteins in each condition. Densitometric quantitation of relative APRO4 expression is indicated underneath each lane of the top panel. (B) Serum starved PC12 cells were stimulated with FGF (25 ng/ml) for the indicated times, and analysed by co-immunoprecipitation (IP) followed by immunoblotting (IB) with anti-phospho-Y416, anti-Src and anti-APRO4. Immunoblotting with Src antibody confirmed that equivalent amounts of Src were present in immunoprecipitates reactions. Densitometric quantitation of relative Src phosphorylation is indicated underneath each lane of the top panel. Data are representative of three independent experiments.