Figure 2.

Secretion of IL-8 by the tumor-associated stroma was extracellular signal-regulated kinases (ERK) dependent. (A) Western blot analysis of TAS cells treated with nicotine (50 µM) for the indicated time demonstrated phosphorylation, signified by “p-“, of ERK but no change in protein kinase B (Akt) or Proto-oncogene tyrosine-protein kinase Src (Src). (B) TAS cells were then pre-treated with an escalating dose of U0126, an inhibitor of MAPK/ERK kinase (MEK) that phosphorylates ERK, and then with nicotine or control 1 h later. MEK inhibition decreased IL-8 secretion in the nicotine-treated TAS cells. IL-8 secretion decreased with an increasing dose of U0126. The uncropped blots and molecular weight markers are shown in Figure S1 and Table S1.