FIG. 10.

c-Cbl can differentiate ErbB1 in homodimers from ErbB1 in ErbB1-ErbB2 heterodimers. COS7 cells were cotransfected with p75.kdB1.R1.Flag and p75.B1.F2.HA (lanes 1 to 3 and 7 to 9) or p75.B2.F2.HA (lanes 4 to 6 and 10 to 12). The cells were stimulated with indicated amounts of rapamycin (nanomolar), and 1.5 mg of lysate was used for immunoprecipitation (IP) with anti-Flag antibodies (lanes 1 to 6) or anti-Cbl antibodies (lanes 7 to 12) and immunoblotted with anti-pTyr antibodies (upper panel). The c-Cbl portion of the blot (lanes 7 to 12) was stripped and reprobed with anti-Cbl antibodies (lower panel).