KRAS and pancreatic ductal adenocarcinoma: Besides c-Myc, Kirsten rat sarcoma viral oncogene homolog (Kras), a small GTPase transductor protein, is the other well-known oncogene with a high mutation rate among all cancers, including pancreatic ductal adenocarcinoma, nonsmall-cell lung cancer, and colorectal cancer (reviewed in 26, 27).