Fig. 6. Effects of EGFR and Src inhibitors on p120 Y228 phosphorylation. (A) A431 cells were treated for 1 hour with DMSO alone or DMSO containing the indicated inhibitors. Drugs concentrations were as follows: AG1478, 300 nM; EKI, 1 µM; PP1, 5 µM; SU6656, 10 µM. Cells were then washed for 2 minutes with PBS containing pervanadate, then lysed with RIPA containing pervanadate. Cell lysates were blotted with mAb pY228 (pY 228) or mAb pp120 (p120). EGFR was immunoprecipitated from whole cell lysates and western blotted with antibodies to phosphotyrosine (EGFR, PY20) or EGFR (EGFR). (B) A431 cells were prepared as described in A, except that cells were treated with increasing concentrations of SU6656 as indicated. Whole cell lysates were western blotted with mAb pp120 or mAb pY228.