Antigen shedding by human breast-cancer cells in vitro and in vivo.

Human breast cancer cells were adapted to chemically defined medium in order to recover naturally shed glycoproteins. Sephadex G-150 chromatography of these glycoproteins revealed 1 major and 2 minor peaks. When the cells were grown in the presence of 3H-leucine, the radioactive shed proteins had a Sephadex profile identical to the unlabelled shed glycoproteins. PAGE analysis of these proteins showed 5 major bands. Antigenically similar proteins were found in the serum of female nude mice bearing BOT-2 tumours, but not in controls.