PGR and breast cancer: From 1,211 breast cancers, 15 oestrogen receptor (ER) negative-progesterone receptor (PgR) positive breast cancers by conventional dextran coated charcoal steroid binding assays in cytosol were reassessed using Elisa techniques with monoclonal antireceptors antibodies in the cytosolic and nuclear fractions, and immunocytochemistry on cryostat sections.