PI3K catalytic alpha polypeptidegene, PIK3CA, as an important member of the PI3K family, has been found to have a high frequency of point mutations in various malignant tumors such as colon cancer,4 stomach cancer,5 neck squamous cell carcinoma6 and ovarian cancer,7 and is one of the most mutation-prone oncogenes discovered so far. The gene discussed is PIK3CA; the disease is gastric cancer.