In particular by Sanger sequencing we analyzed: EGFR (exons 18, 20, and 21) in lung adenocarcinomas and breast carcinomas; KRAS (exons 2, 3, and 4) in colon, lung, pancreas, biliary tract adenocarcinomas; BRAF (exon 15) in colon, lung, pancreas, biliary tract adenocarcinomas, and melanomas; NRAS (exons 2, 3, and 4) in colon adenocarcinomas, and melanomas; PIK3CA (exons 9 and 20) in colon adenocarcinomas and breast carcinomas. The gene discussed is PIK3CA; the disease is colon adenocarcinoma.