Immunohistochemical detection of ras p21 oncoprotein in breast cancer imprints

We examined the expression of ras p21 oncoprotein using monoclonal antibody Y13 259 and applied the streptavidin-biotin method. A total of 79 imprints of breast lesions were taken during frozen section. Our purpose was evaluation of the staining intensity, at the cellular level, without the technical disadvantages of formalin-fixed, paraffin-embedded tissues. Of the 79 imprints examined, 37 were carcinomas of ductal origin (not otherwise specified type), 8 were lobular and 3 mixed. Additionally, 20 imprints from adjacent normal tissue as well as 11 fibroadenomas (simple and hyperplastic) were assessed. Our results showed the following: (1) the positivity of all cancer cells ranged from + to + + +, (2) positivity did not show any significant difference among cancer types, (3) in increasing the tumor grade, staining intensity was increased, (4) whenever benign epithelial cells were present, their expression was low or mild, (5) only hyperplastic fibroadenomas showed weak positivity, and (6) almost all the inflammatory components were constantly negative.