SCF-induced interactions between KIT and Cbl's requires the KIT juxtamembrane SH2 docking site and the Cbl-b TKB domain. (A) TKB domain of Cbl-b and Y568/Y570 in KIT are essential for SCF-induced interaction between Cbl-b and KIT and tyrosine phosphorylation of Cbl-b. Cell lysates used in Figure 4B were subjected to immunoprecipitation with anti-HA antibody followed by blotting as in Figure 4B. (B) Y568/Y570 in KIT is essential for SCF-induced tyrosine phosphorylation of c-Cbl and is important for interaction between c-Cbl and KIT. Cell lysates were subjected to immunoprecipitation with anti-HA antibody followed by blotting as in panel A. Considering that the level of c-Cbl in SCF-stimulated cells is much lower than that in nonstimulated cells, the induction of association between KIT and c-Cbl by SCF is very apparent.