Catenins are proteins that are linked to the cytoplasmic domain of transmembrane cadherins. p120 Catenin is a nucleolar protein belonging to the armadillo protein family, which are involved in cell-cell adhesion and signal transduction. p120 Catenin is associated with proliferation, and is found in the majority of human malignant tumors, while remaining absent from resting normal cells. Anti-p120 Catenin is useful in differentiating between ductal and lobular neoplasia in the breast. In breast lobular neoplasia, p120 Catenin shows a diffuse cytoplasmic immunostaining pattern, while breast ductal neoplasia retains the membrane immunostaining pattern. p120 Catenin is useful in differentiation of lobular carcinoma from ductal carcinoma of the breast and in identifying early lesions of lobular neoplasia.

Strong staining with Anti-p120 Catenin is associated with discohesive infiltrative morphology in gastric and colonic carcinoma. Accumulation of p120 Catenin in the cytoplasm has been linked to lung cancer, pancreatic cancer, and gastric cancer, and is correlated to poor prognosis in colon cancer.