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; reacts with VNTR20 recombinant unglycosylated fragment of MUC1 protein (and very weakly with monomeric MUC1 peptide), with deglycosylated and underglycosylated natural MUC1 (but not with completely glycosylated natural milk MUC1). 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. Also 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. They may be used in conjunction with MAbs M9E7, M8C9, M10G4 and M10H6 specific to unglycosylated VNTR region of MUC1 as capture reagents..