Résumé
Human breast cancer is characterized by its estrogen dependence, observed in 30 to 50% of the patients, and by its high frequency of metastasis. Moreover, in several estrogen-responsive and -unresponsive human breast cancer cell lines, factors involved in the control of cell proliferation and tumor invasion have been identified and used to develop antibodies allowing direct studies in mammary tumor biopsies. One fruitful approach to identifying such factors has been to detect the proteins, enzymes, and factors secreted in conditioned media by estrogen-receptor-(RE)-positive breast cancer cells following their stimulation by estrogens.