Figure 2. Figure 3: Immunohistochemical analysis of p53 protein expression in carcinoma of the breast.

(a) A breast tumor displaying a more generalized and intense p53 nuclear staining. A diffuse pattern of staining was identified in the cytoplasm of tumor cells. The labelled cells for the p53 show a brown precipitate, a green staining underlines nuclei of unlabelled cells.

(b) The positive cases demonstrated characteristic staining patterns that were either predominantly nuclear or both nuclear and cytoplasmic. P53 is located at the cytoplasmic surfaces of the nuclear envelope. Different structural systems of the nucleus are targets for p53. Nuclear p53 is found in the nucleoplasm, chromatin fraction and also attached to the nuclear matrix. Insert: focal staining showing the fine nucleolar distribution characteristic of p53. DAB staining is prevalent throughout the nuclear bodies.

(c) Breast carcinoma cells show negative staining for p53. Unlabelled nuclei show only counterstain, indicated by the blue color.

Avidin-biotin immunoperoxidase technique on frozen sections counterstained with methyl green (a, b) or haematoxylin (b insert, c). All panels were photographed at the same magnification.