EGFR exposed to cigarette smoke cannot bind c-Cbl and is not ubiquitinated. Serum-starved HAE cells were untreated (NT) or incubated with 100 ng/ml EGF for 15 min, 1 U/ml GO for 30 min, or smoke from 1 cigarette (CS) for 45 min. Cells were lysed and A, the EGFR was immunoprecipitated (IP) from cell lysates using anti-EGFR mAb 225. B) EGFR was immunoprecipitated with anti-EGFR mAb 225 and Grb2 was immunoprecipitated with anti-Grb2 Ab. Immunoprecipitated proteins were separated by SDS-PAGE, transferred to a nitrocellulose membrane, and immunoblotted (IB) with the indicated Abs. Ub, ubiquitin; p-EGFR, phospho-EGFR.