Genetic changes, including KRAS, p53, PIK3CA, ARID1A, and MLL mutations, as well as ERBB4, CD44, PIK3CA, and C-MET amplifications, are often identified in GC implying that they may have critical tumorigenic roles in gastric carcinogenesis [32,33,34,35]. The gene discussed is PIK3CA; the disease is gastric cancer.