[P21 expression of ras oncogene product in benign and malignant female mammary lesions].

The level of P21 protein in 40 breast carcinomas, 37 benign tumors and 52 proliferative breast diseases in females were determined by the ABC immunohistochemical method. The positive rate was 72.5%, 32.43% and 23.07% respectively. The positive expressions were mainly found in tumor cells in poorly differentiated infiltrating ductal carcinomas and in 3 of the 5 proliferative breast disease cases with atypical hyperplasia of ductal epithelium, suggesting that P21 protein detection could provide a molecular biological basis for the evaluation of malignant changes and the prognosis of mammary lesions.