Polypeptide composition of normal and neoplastic human breast tissues and cells analyzed by two-dimensional gel electrophoresis.

The protein populations of epithelial cells cultured from two neoplastic and five non-neoplastic human breast tissues were resolved and displayed by two-dimensional polyacrylamide gel electrophoresis and silver-staining. With a computer-based image analysis system, we identified eight polypeptides which are present in both of the neoplastic cell lines, but absent from all five of the cultures of non-neoplastic breast cells. The eight polypeptides are not unique to cells cultured from neoplastic breast, because they are also found in cells cultured from non-breast tissues, both neoplastic and non-neoplastic. Two of the eight polypeptides (approximately Mr 25,000/pI 4.4 and approximately Mr 31,000/pI 5.5) are present in the patterns of whole tissue samples from infiltrating ductal carcinomas and absent in most normal breast tissue.