Antibodies to the estrogen induced 52 K protein released by human breast cancer cells

Polyclonal antibodies against an estrogen induced 52 K protein released by human breast cancer cells have been developed by injecting rabbits with a crude cellular pellet of MCF7 human breast cancer cells. The rabbit antisera have been tested against [35S]Methionine labelled proteins released by the MCF7 cells followed by separation of the immune complexes with Protein A Sepharose. In spite of their low specificity and titer, these antisera allowed us to investigate the release of the 52 K protein in vitro by other mammary cancer or normal cells.