FIG. 5.

Interactions between signaling proteins and endosome-associated EGFR in BT20 cells. (A) BT20 cells were treated with AG-1478 and EGF with or without monensin as described in Materials and Methods. The cells were washed and then incubated with serum-free medium for the indicated times. The cells were lysed and immunoprecipitated (IP) with a rabbit anti-EGFR antibody as described in Materials and Methods. Immunoprecipitates were subjected to immunoblot analysis with mouse anti-EGFR, anti-Grb2, anti-SHC, and anti-p85α antibodies. BT20 cells that were serum starved or treated with EGF, monensin, or EGF plus monensin were used as controls.