VISUALIZATION OF TISSUE KALLIKREIN IN HUMAN BREAST-CARCINOMA BY 2-DIMENSIONAL WESTERN BLOTTING AND IMMUNOCHEMISTRY

Tissue kallikrein is well known to liberate the vasoactive peptide kal lidin from L-kininogen. Recently it was reported to activate matrix de grading metalloproteinases in vitro and to be present in gastric carci noma cells. By immunohistochemistry we localized tissue kallikrein in the cytoplasm of ductal breast cancer cells. In addition, two-dimensio nal Western blotting was used to further characterize its biochemical properties. By this method immunoreactive tissue kallikrein was found to have a molecular mass of 25 kDa and an isoelectric point close to p H 6. Furthermore its presence in human milk could be demonstrated.