MUC4 and pachyonychia congenita: While by serving as an immunomodulatory switch, members of the glycoprotein family, such as MUC1, can play either a pro- or anti-inflammatory role in various infection-induced malignancies [5,176], MUC4 plays an important role in the etiology of many different types of cancer, including pancreatic cancer (PC), ovarian cancers, and head and neck cancers (HNC) [114,152].