Figure 3

Analysis of mRNA levels of HER1 ligands. Relative mRNA levels of A) AREG and B) TGF-α were determined in HMEC parental HER1 (diamonds), HER2 (squares) and HER3 (triangles) cell lines using quantitative RT-PCR, as described in the Methods. Total RNA was extracted from cell samples treated with 12 ng/ml EGF for 0, 0.5, 2, 8 or 24 h. mRNA expression for each gene was normalized with respect to its expression in the parental HER1 cells at t = 0 h. Data points and crossbars represent the mean and standard deviation of three replicates, each from a separate culture dish. The symbols denote statistically significant differences between the parental HER1 and HER2 (*) or HER3 (#) by both analysis of variance and Fisher's protected least significant difference analysis.