Tyrosine phosphorylation of RAFTK in TrHBMEC after cytokine treatment. Cells were serum-starved overnight and then treated with VEGF (A), VRP (B), OSM (C), or bFGF (D) for the indicated time periods. TCL (1 mg) from treated or untreated cells were immunoprecipitated with anti-RAFTK antibody. Immunoprecipitates were resolved on 7.5% SDS-PAGE and subjected to serial immunoblotting with the antiphosphotyrosine antibody 4G10 (top panel) and anti-RAFTK antibody (bottom panel). NRS was used as a negative control. There was a 200% to 500% estimated increase in phosphorylation after cytokine treatment.