KRAS and familial pancreatic carcinoma: Mutations in all four clinically relevant isoforms of Ras (H-Ras, N-Ras, and splice variants K-Ras-4A and K-Ras-4B) are known to cause a variety of cancers, with K-Ras being the most frequently mutated isoform in pancreatic cancer (COSMIC database, Sanger Institute).