Mutation at codon 201 of GNAS was only observed in IPMNs with a mutation rate of 41–75%, leading to sustained activation of a heterotrimeric Gs protein (GSP) and an increased level of cyclic adenosine monophosphate glycoside (cAMP), which activates protein kinase A (PKA) with subsequent cancer-promoting activity [68]. The gene discussed is GNAS; the disease is cancer.