Figure 2.

Thrombin-induced epidermal growth factor (EGF) receptor (EGFR) and ErbB2 transactivation requires EGFR kinase activity. (a and b) MDA-MB-231 cells were pretreated with 0.1% dimethyl sulfoxide (DMSO) or 2 µM AG1478 for 2 h at 37 °C. Cells were then incubated with or without 10 nM thrombin or 16 nM EGF for 4 min at 37 °C and EGFR and ErbB2 tyrosine phosphorylation was detected as described in Figure 1. The data are expressed as fold increase over untreated control and are representative of three independent experiments. (c) MDA-MB-231 cells labeled with myo-[³H]inositol were incubated with 0.1% DMSO, 2 µM AG1478 or 1 µM PD153035 for 2 h at 37 °C. Cells were then stimulated with 100 µM TFLLRNPNDK for 60 min at 37 °C and the amounts of [³H]inositol phosphates generated were then measured.