Auto-phosphorylation of EGFR* and EGFR-L858R is efficiently inhibited by EGFR TKIs. A, murine Ink4a/Arf−/− Pten −/− astrocytes transduced with control or indicated EGFR mutants were serum starved for 24 hours followed by 4-hour treatment of vehicle (DMSO), 250 nM erlotinib or 50 nM gefitinib. Cell lysates were prepared and subjected to immunoblot analysis. Note, the molecular weight of EGFR (wt) and EGFR-L858R is ~170KD and EGFR* ~140 KD. B and C, cell lysates from the indicated treatments as in (A) were immunoprecipitated with anti-EGFR (B) or anti-phospho-tyrosine antibody (PT-66) (C), and immunoblot analysis was performed using anti-phospho-tyrosine (4G10) (B) or anti-EGFR (C) antibody, respectively.