Specific for human MUC1 glycoprotein (peptide tandem repeat in MUC1 core). Affinity > 1 x 108. Binds with high efficiency with different epitopes within the VNTR tandem repeat peptide region of MUC1 molecule, which have different conformations and peptide- carbohydrate compositions; efficiently recognize underglycosylated and natural MUC1 protein isolated from human milk by affinity chromatography; belong to MAb clusters 6 and 7 according to ISOMB TD-4 classification. Non crossreactive with normal serum proteins and human tissues of non-epithelial origin. Can be used for immunohistochemical staining of paraffin and frozen sections of breast, lung and ovarian tumor tissues. They may be used for staining of paraffin-embedded tissue sections fixed in neutral-buffered formalin and is compatible with commonly used histological fixatives. Can be used in the form of enzyme conjugates for development in ELISA sandwich assays of under-glycosylated tumor-associated MUC1 mucins in human serum in conjunction with MAbs M9E7, M4H2, M8C9, M10G4 and M10H6 specific to unglycosylated VNTR region of MUC1 as capture reagents.