Figure 4. HB-EGF increases the tyrosine phosphorylation of ERK1/2

A: HB-EGF caused a dose-dependent increase in the amount of phosphorylated ERK-1 and ERK-2 (below) while the total amount of ERK-1 and ERK-2 protein expressed by the cells remained unchanged (above). B: Influence of the selective receptor tyrosine kinase blockers (AG1478 [300 nM] and AG1296 [10 μM]) and inhibitors of protein kinases (PD98059 [40 μM], UO126 [4 μM], SB203580 [10 μM], and LY294002 [5 μM]) on the HB-EGF induced activation of ERK-1 and ERK-2. The cultures were preincubated with the blockers for 30 min and then stimulated with HB-EGF for 10 min. The data are representative of two independent experiments.