Discrimination of Mitotic Cells Using Anti‐p105 Monoclonal Antibody to Analyze the Mode of Action of Etoposide and Podophyllotoxin in Human Gastric Cancer Cells

Anti‐p105 monoclonal antibody was used to discriminate between M‐phase and G2‐phase of gastric cancer cells. P105 is a proliferation‐associated nuclear antigen and its expression increases with cell cycle progression, especially in the mitotic phase. As an example of cell cycle analysis, the modes of action of etoposide and podophyllotoxin were examined by multiparameter flow cytometry. We found that etoposide caused G2 block and retarded S phase transit and podophyllotoxin caused potential M phase block in gastric cancer cells. This cell cycle analysis by using anti‐p105 monoclonal antibody should be useful for analysis of the actions of anti‐tumor agents, especially for M phase analysis, because of its convenience and reliability.