Fig. 2. Electroporation of a synthetic Grb2-SH2 blocking peptide or compound 8 inhibits Grb2 binding to growth factor receptors. The Grb2-SH2 binding peptide containing Pmp at the position of phosphotyrosine (Lanes 2 and 5), a control phenylalanine-containing peptide (Lanes 3 and 6), or compound 8 (Lane 7) was electroporated into mouse NIH-3T3 fibroblasts (Lanes 1–3), human lung carcinoma A549 cells (Lanes 4–6), or NIH-3T3-methu cells (Lanes 7–9). Cells were subsequently stimulated with PDGF (Lanes 2 and 3), HGF (Lanes 5 and 6), or EGF (Lanes 8 and 9), as indicated. Lanes 1, 4, and 8, unstimulated controls. Detergent cell extracts were precipitated with a Grb2-specific antibody, and proteins were resolved by PAGE and transferred to a nitrocellulose membrane probed with antibodies to phosphotyrosine (Lanes 1–3), Met (Lanes 4–6), or EGFR (Lanes 7–9). Horizontal bar, the position of the Mr 116,000 marker.