PURPOSE: Mounting evidence suggests that alterations of Akt/protein kinase B (PKB) play an important role in tumorigenesis. Phosphorylated Akt regulates many of the key effector molecules involved in apoptosis, angiogenesis, and cell-cycle progression during tumorigenesis. The expression of phosphorylated Akt has been described in some human malignancies, but not in primary human gastric cancer. The purpose of this study was to explore the expression status of phosphorylated Akt protein in gastric carcinomas. MATERIALS AND METHODS: In the current study, we analyzed the expression of phosphorylated Akt protein in 60 advanced gastric adenocarcinomas by using immunohistochemistry and a tissue microarray approach. RESULTS: Immunopositivity (defined as > or =30%) was observed for the phosphorylated Akt in 42 (70%) of the 60 cancers. Normal gastric mucosal cells showed no or weak expression of phosphorylated Akt protein. CONCLUSION: Taken together, these results indicate that Akt is frequently activated in gastric adenocarcinoma cells and suggest that phosphorylayed Akt may play a role in the development of human gastric adenocarcinomas.