Furthermore, beta-adrenoceptor antagonists have been shown to reverse the stimulatory action of nicotine on the expression of protein kinase C, extracellular signal-regulated kinase-1/2 phosphorylation, and cyclooxygenase 2 together with cell proliferation in gastric cancer cell line (AGS) (Shin et al., 2007). Here, PTGS2 is linked to gastric cancer.