Estrogen receptor and alpha-fetoprotein in human breast cancer: brief communication.

Concentrations of estrogen receptor (ER) and alpha-fetoprotein were determined by dextran-coated charcoal assay and analyzed with Scatchard plots and radioimmunoassay, respectively, in cytosols of 72 human breast cancers. The values for ER ranged from 0 to 340 fmoles/mg cytosol protein. The concentrations of alpha-fetoprotein, which were low in all tumor cytosols examined, ranged from less than 0.1 to 1.1 ng/mg cytosol protein. No positive relationship was found between ER and alpha-fetoprotein concentrations. These results show that ER, but not alpha-fetoprotein, usually accounts for most of the high estrogen-binding capacity in cytosols of human breast cancers.