Fig. 4. HGF/SF increases cellular amounts of serine-phosphorylated transcription factor Sp1. Western blot analyses of HaCaT cells that were left untreated (media change) or were stimulated by HGF/SF (10 minutes at 100 ng/ml). Cellular extracts were immunoprecipitated (IP) by a specific anti-Sp1 antibody (Sigma) prior to immunoblotting (IB). (A) Immunoblotting with Sp1 antibody (upper panel) and phospho-serine monoclonal antibody (clone 4A3; lower panel). (B) Immunoblotting with Sp1 antibody (upper panel) and phospho-threonine antibody (lower panel). The immunoblots displayed are representative of three that were performed revealing comparable results.