Recently, microarray and other gene expression profile studies have been performed, showing that at the gene expression level, Barrett’s esophagus has strong similarities with normal squamous esophagus and gastric cardia. Nevertheless, the signal transduction events that occur in Barrett’s esophagus are poorly understood. Therefore, peptide arrays, exhibiting 1176 specific consensus sequences for protein kinases, were used to produce a global analysis of cellular kinase activity in biopsies of Barrett’s esophagus. The results were compared with the neighboring gastric cardia and normal squamous epithelia. Provisional signal transduction schemes showing the differences in cellular signaling were constructed. The results indicate that the activity of the MAPK signaling cascade was significantly decreased. Additionally, an enhanced glycolytic activity was found in Barrett’s esophagus. Furthermore, the EGF receptor was significantly more activated in normal squamous esophagus compared to Barrett’s esophagus. These data confirm that Barrett’s esophagus does not represent a true transdifferentiation, but is indeed an incompletely differentiated type of epithelium that has strong similarities with the two different surrounding types of tissue. Manipulations of several of these cellular events may possibly lead to a more effective treatment of Barrett’s esophagus. For details, see the article by van Baal et al. on page 11605 of this issue.

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