Figure 5

Deregulated ERK signalling in metaplastic epithelial cells. A. Paired cultures of epithelial cells (EC-85) were analyzed by immunoblotting for cytokine-mediated phosphorylation of STAT1, STAT3 and ERK. Basal level of phosphorylated ERK but not of phosphorylated STATs is elevated. B, Expression of EGFR, STAT3 and ERK in the untreated cultures was determined by immunoblotting. C, Cultures of normal and metaplastic cells were treated for 3 h with serum-free RPMI containing 0.1% carrier DMSO or the same medium with 10 μM U0126. The level of phosphorylated ERK was determined by immunoblotting. D, DNA synthesis was determined in response to treatment with serially diluted OSM and conditioned medium of LPS activated macrophages. One set of cultures of normal and metaplastic cells were also treated for 3 hour with 10 μM U0126 in normal growth medium prior to the addition of [³H]thymidine. The incorporation of [³H]thymidine (mean and range of duplicate cultures) were normalized to the number of cells and expressed relative to the values determined for the control cultures of the normal epithelial cells.