MUC2 and mucinous adenocarcinoma: Earlier, a study showed that in a BC patient cohort, MUC2 was expressed in all mucinous carcinomas, 11.2% of invasive ductal carcinomas, and none of the invasive lobular and medullary carcinomas [155], whereas MUC1 was expressed in invasive BC, but not in medullary carcinomas.