KRAS and pancreatic ductal adenocarcinoma: Likewise, it was established that pancreatic ductal adenocarcinoma (PDAC) development requires certain mutations; namely, mutation of the GTPase Kras (KRAS) oncogene and mutations of tumor suppressor genes, cyclidin-dependent kinase inhibitor 2A (CDK N2A), tumor protein p53 (TP53), a small mothers against decapentaplegic (SMAD) protein family member 4 (SMAD4) [8,9].