KRAS and pancreatic ductal adenocarcinoma: Although there are high differences in the mutated isoforms (HRAS, NRAS or KRAS) and mutational frequency across different tumour types, mutations in the KRAS isoform can be found in 95% of pancreatic ductal adenocarcinoma and the vast majority of colon and lung tumours, while the rates of oncogenic mutation occurring in the NRAS and HRAS isoforms are much lower [22].