By using mass spectrometry, we detected the interaction of DIAPH3 with key proteins related to various selenoamino acid metabolism pathways in pancreatic cancer cell lines, such as RPS8, IARS, RPL4, RPL6, and RPS2, which suggested that we can inhibit the progression of pancreatic cancer by regulating the metabolism of selenoamino acids. This evidence concerns the gene DIAPH3 and familial pancreatic carcinoma.