Fig. 3. Identification of the binding site in RET crucial for interaction with SH2-Bß. HEK293T cells were co-transfected with wild-type RET or the indicated RET mutants, together with GFR1 and SH2-Bß; cells were then stimulated with 100 ng/ml GDNF for 10 minutes. Cell lysates were immunoprecipitated with anti-RET or anti-SH2-Bß antibodies, followed by immunoblotting with anti-SH2-Bß or anti-RET antibodies. Mutation of Tyr981 to Phe severely attenuates the interaction between RET and SH2-Bß. WT, wild type; K, lysine; M, methionine; Y, tyrosine; F, phenylalanine.