P70S6 kinase α and β isoforms expression in cell lines and breast tumors

P70 kinase of S6 ribosomal protein represented by α and β isoforms is among the key enzymes participating in the protein synthesis activation mediated by mitogenic signals. The expression of two p70S6 kinase isoforms in several cell lines as well as in malignant and non-malignant breast tumors was analyzed. The expression of both p70S6 kinase forms increased in all breast tumor cell lines examined. The enhanced synthesis of α and β isoforms in malignant tumors may reflect their important role in cancerogenesis. The increased levels of S6Kα expression comparable in malignant and non-malignant tumors have been shown for the first time.