Fig. 4

TNF-α-induced VCAM-1 expression is mediated through c-Src-dependent transactivation of EGFR. a, b Cells were pretreated with various concentrations of AG1478 (EGFR inhibitor; 0.1, 1, or 10 μM) for 1 h and then incubated with TNF-α for 16 h (a) or 4 h (b). c Time dependence of TNF-α-induced EGFR phosphorylation, cells were treated with TNF-α (15 ng/ml) for the indicated time intervals in the presence or absence of AG1478 (10 μM). d Cells were transfected with siRNA of EGFR or scramble (scrb, as a control) for 24 h and then incubated with TNF-α for 16 h. e Cells were treated with TNF-α for the indicated time intervals in the presence or absence of TNFR nAb (3 μg/ml) or PP1 (1 μM). The VCAM-1 protein (a, d), and mRNA and promoter activity (b) were analyzed by Western blotting, real time-PCR, and promoter assay, respectively. The EGFR phosphorylation (c, e) was analyzed by Western blot. Data are expressed as mean ± SEM of three individual experiments (n = 3). ^* P < 0.05, ^# P < 0.01 vs. TNF-α alone