PIK3CA and gastric cancer: We further explored the clonality of recurrently mutated genes identified in ACGEJ or gastric cancer samples (7, 53–56) and found that mutations of PIK3CA (E545K), TP53 (R248Q), SOX9 (Q369P) and NEFH (V267M) were located in the dominant founding clone, indicating that mutations in these genes were acquired at an earlier time point (Figure 3E).