The expression level of NF1 in digestive system tumors, including CHOL (Cholangiocarcinoma), LIHC (Liver hepatocellular carcinoma), PAAD (Pancreatic adenocarcinoma), and STAD (Stomach adenocarcinoma), was found to be higher than that in the adjacent non-cancerous tissue (Additional file 3: Fig. S1A). This evidence concerns the gene NF1 and cholangiocarcinoma.