NTRK1 and neoplasm: Approximately 22% of examined tumours in the TCGA study and ACRG study were classified as microsatellite unstable (MSI) tumours, displaying numerous mutations in receptor tyrosine kinase (RTK) and RAS signalling pathways (EGFR, ERBB2, ERBB3, JAK2/PD-L1/2, FGFR2, MET, VEGFA, KRAS/NRAS, RASA1) and in the PI(3)-kinase pathway (PIK3CA and PIK3R1) and frequent truncating mutations in PIK3R1 and PTEN [22,23].