Figure 4: Tyrosine kinase inhibitors inhibit EGFR phosphorylation in response to TNF-α. HT-29 cells were treated with 2 μM PP2 (Src-kinase inhibitor), 100 μM genistein (tyrosine kinase inhibitor), or 10 μM AG1478 for 15 mins prior to 15 mins of TNF-α treatment. The EGF receptor was immunoprecipitated and tyrosine phosphorylation assessed (a). Both PP2 and genistein abrogated TNF-α-dependent EGFR tyrosine phosphorylation. In contrast, neither PP2 nor genistein had an appreciable effect upon TNF-stimulated ERK1/2 phosphorylation (b) and (c). Data are representative of at least three experiments.