Fig. 3. TCPTP binds to VEGFR2. (A) HEK293 cells transiently transfected with VEGFR2 and a substrate-trapping mutant of TCPTP (TC45-D182A) were treated with VEGF (100 ng/ml, 5 minutes). Cell lysates were immunoprecipitated (IP) with anti-TCPTP or control (IgG) antibodies and blotted for VEGFR2 and TCPTP as indicated. Aliquots of the lysates were also analyzed to control for equal protein expression. (B) HEK293 cells transfected as in A, or an untransfected control, were treated with VEGF or left untreated. Immunoprecipitations were performed with anti-VEGFR2 or control (IgG) antibodies and blotted as indicated. The co-immunoprecipitations were done in the presence or absence of 100 µM sodium orthovanadate (Na₃VO₄) as indicated. Note the disappearance of the co-immunoprecipitated TCPTP when sodium orthovanadate is present.