To test the hypothesis that aspirin's anti-cancer effects might differ by PIK3CA mutation status, we investigated the anti-proliferative activity of aspirin at physiologically attainable concentrations in seven PIK3CA-mutant and six PIK3CA-wild-type colon cancer cell lines (Table 1) using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H- tetrazolium inner salt (MTS) assay. The gene discussed is PIK3CA; the disease is malignant colon neoplasm.