CSC-induced phosphorylation of Extracellular signal Regulated Kinases (ERK1/2) 1/2. NCI-H292 cells (A and C) were stimulated with medium, TGF-α, and CSC (10, 5, 2 and 1 AU/ml) for 15 minutes, 6 and 24 hours (A) or with medium, TGF-α, and 2 and 1 AU/ml of CSC in presence (C) or absence (A) of NAC. PBEC were stimulated with medium, TGF-α and CSC (10, 5, 2 and 1 AU/ml) for 15 minutes and 24 hours (B). Next cellular lysates were prepared, and used to detect the level of total (t-ERK1/2) and phosphorylated ERK1/2 (p-ERK1/2) using Western blot analysis. The results shown in each panel are from one experiment that was repeated three times with similar results. To assess the role of EGFR in CSC-induced ERK1/2 phosphorylation, NCI-H292 cells were preincubated for 1 hour with 1 μM AG1478, and incubated for 15 minutes or 6 hours with medium alone or with CSC (10 AU/ml) (D).